Physics
question1
A mirror's focal length is the distance along the principal axis to the focal point, the location where incident rays parallel to the principal axis converge to or diverge from. Concave (converging) mirrors have their reflective surface curved inward, and they converge light rays to form real images in front of the mirror. Convex (diverging) mirrors have their reflective surface curved outward, and they diverge light rays to form virtual images behind the mirror. The radius of curvature R of a spherical mirror is twice the=2 focal length f: R=2f Of the given options, only mirrors C and D are convex and create virtual images. Because the light rays in mirror D are reflected away at a smaller angle, these rays can be traced back behind the mirror to a more distant focal point than that traced by the light rays in mirror C. Because the radius of curvature is twice the focal length, mirror D also has a larger radius of curvature than mirror C. concept: Concave (converging) mirrors create real images when the object is placed outside the mirror's focal length, whereas convex (diverging) mirrors always create virtual images. For spherical mirrors, the radius of curvature is twice the focal length: f=R2
question 37
Dark bands (minimum light intensity) due to destructive interference occur when diffracted light waves pass through the slit at angles (θ) that are a function of the slit width and an integer multiple (m = ±1, ±2, ±3...) of the wavelength: sin θ = mλ/a According to this relationship, decreased slit width or increased wavelength tends to widen the band pattern such that greater distances are present between light and dark bands. Conversely, increased slit width or decreased wavelength results in a relatively narrow band pattern. Therefore, both slit width and wavelength influence the angle of propagation associated with the dark and light bands in the pattern of diffracted light concept: Single-slit diffraction is an optical phenomenon that demonstrates the waveform nature of light. The band pattern associated with a given diffraction event is related to slit width and the wavelength of light.
question5
Dispersion refers to the phenomenon of different frequencies of light having slightly different refractive indices. Light with higher frequency (such as violet light compared to red light) has a higher index of refraction in a lens and therefore refracts more. The formation of blurry images due to dispersion is known as chromatic aberration.
question 29
For a closed pipe you would use the equation L = wavelength/4 concept: For a pipe open at both ends, the length is half the fundamental frequency wavelength (L = λ/2). From the wave velocity equation (v = λf), frequency is calculated by dividing the wave's velocity by its wavelength.
q28
Had to go thru all the current equations and then match up the units (image) concept: Current is defined as the movement of charge per unit of time. The current within a circuit may be expressed in terms of coulombs per second, volts per ohm, or watts per volt.
question 34
Have to know that the relationship btw intensity and radius is inversely proportional to the square of the distance btw the source and the detector concept: The intensity of sound waves is defined as power per unit area, and relates to the perceived loudness of sounds. Intensity is inversely proportional to the square of the distance between source and detector, resulting in a relatively significant decrease in intensity as the distance increases.
question2
In this question, two convex lenses each with an individual magnification of 3 are placed in series and spaced such that the image of the object produced by the first lens becomes the image magnified by the second lens. Applying the equation for total magnification for this system gives: Mtotal=M1⋅M2=3⋅3=9 Therefore, the total magnification produced by such a two-lens setup would be equal to 9. concept: Magnification is the phenomenon in which a lens produces an image that is enlarged or shrunken relative to the original object. Multi-lens systems arranged in series provide a combined magnification equal to the product of all individual lens magnifications.
Snells law refraction
Lower refraction (higher speed) --> Higher refraction = ray bends TOWARDS the normal (think about giving head)
Question 3
Needed to know the electromagnetic spectrum The electromagnetic spectrum may also be ordered in terms of the energy (E) associated with a given electromagnetic waveform, which can be expressed in terms of either electromagnetic frequency or wavelength using Planck's constant (h) and the speed of light (c) as: E = hf = hc/λ Accordingly, the energy of electromagnetic radiation is inversely proportional to wavelength and directly proportional to frequency. Radiation types arranged from lowest energy to highest energy: Radio waves < Microwaves < Infrared light < Visible light < Ultraviolet light < X-rays < Gamma rays < Radio waves < Microwaves < Infrared light < Visible light < Ultraviolet light < X-rays < Gamma rays concept: The electromagnetic spectrum consists of radiation types with different wavelengths, frequencies, and energies. Ordering the electromagnetic spectrum in terms of decreasing wavelength is equivalent to ordering the electromagnetic spectrum in terms of increasing energy.
question 2
Passage states that Joule- Thomson effect occurs without heat transfer with the surrounding. That means no heat exchange and thats adiabatic A. temp is constant C. volume is constant so work is 0 (bc of the pressure volume curve where W=PΔV) - also known as isochoric D. pressure is constant concept: Thermodynamic processes that keep important quantities constant are assigned special names. These include isothermal (constant temperature), adiabatic (without external heat transfer), isochoric (constant volume), and isobaric (constant pressure) processes
question6
The Snell law describes the relationship between θ1, θ2, n1, and n2 when light refracts from one medium to another: n1 sin θ1=n2 sin θ2 Setting the left side (1) of the equation as the incident light in air and the right side (2) as the refracted light in the lens: (1)(sin 50°)=(n2)(sin 35°) Solving for the refractive index of the lens n2: n2=sin 50°/sin 35° concept: Refraction is the bending of light as it crosses between media with different indices of refraction. The Snell law (n1 sin θ1 = n2 sin θ2) describes the relationship between the angles of incidence and refraction with the refractive indices of two media.
question3
The frequency f of the first harmonic (n = 1) is called the fundamental frequency (f1), the lowest-frequency standing wave that can be produced within an object. The given wave frequency of the first harmonic is related to velocity (v) and to wavelength (λ1) by the expression f1=v/ λ A distinguishing feature of standing waves is that standing wave characteristics are closely related to the dimensions of the objects in which they are produced. Accordingly, the wavelength (λn) of each harmonic in a string fixed at both ends is proportional to the string length (L): λn=2L/n Using the above equation, the wavelength of the first harmonic (n = 1) may be expressed as λ1=2L Substituting this expression for the wavelength of the first harmonic into the equation relating frequency to velocity and wavelength gives f1=v/2L Therefore, when provided with wave velocity, only the string length would be needed to determine the fundamental frequency. concept: The fundamental frequency of a wave is directly proportional to wave speed and inversely proportional to wavelength. For a string fixed at both ends, the wavelength of each harmonic is proportional to the string length.
question 35
The frequency of these emitted electromagnetic waves must progressively increase and the wavelength must progressively decrease. When emitting across the visible light spectrum from lower to higher energy, the color progression would be red, orange, yellow, green, blue, indigo, and violet. Therefore, the transition is from red light to green light to blue light. Educational objective: The visible light spectrum refers to electromagnetic radiation that may be detected by the human eye, ranging from approximately 750 to 400 nm in wavelength (ie, red to violet). The energy associated with electromagnetic radiation is directly proportional to wave frequency and inversely proportional to wavelength.
q11
The question is asking for the electric field and they give you the voltage and the distance (in cm). E = V/d (in meters) 50cm = .5m 3000/.5 = 6000 (V/m) = 6.0kN/C Units for E can be N/C or V/m concept: An electric field accelerates charged particles, and its magnitude has SI units of newtons per coulomb (N/C), which are equivalent to volts per meter (V/m). The magnitude of a uniform electric field is calculated as its voltage divided by its distance: E = ∆V/d
Q1
The question is asking for the final PE Need to know the total energy is equal to KE final + PE final. Total energy can be found from the KE and PE given in the q stem. And then need to find KE final Subtract the KE final from total energy to get PE final concept: Electrostatic force is conservative; the sum of potential energy and kinetic energy (KE) is kept constant. KE is the product of mass m and the square of velocity v: KE = (1/2)mv^2. Therefore, the potential energy of a particle is the difference between its total energy and its KE.
Mass spec and radius of curvature
The smaller the object, the greater the curvature so smaller the radius
q14
The way i solved this is bc of the equation F=qvBsinΘ Here F is perpendicular to qvB and thats what choice A is explaining Concept: The Lorentz force equation is used to determine the force exerted on a charge in the presence of an electric and magnetic field. The force exerted on a moving charge due to a magnetic field is perpendicular to both the ion's velocity and the direction of the magnetic field.
Sinusoidal functions of waves
They are used to model mechanical waves bc each function contains terms analogous to the fundamental properties of waves
question 33
Thin-film interference refers to the multicolored arrays generated by the reflection events that occur within a system composed of two layers of semitransparent media. The relative intensity of the colors seen within the multicolored array depends on the constructive and destructive interference among waveforms of polychromatic (variable wavelength) light. Thin-film interference is influenced by the thickness of the film because light waves of a specific wavelength (ie, color) that interfere constructively or destructively at one film thickness may no longer interfere in the same fashion at a different thickness. Concept: Thin-film interference describes the multicolored array generated when polychromatic light is incident on an interface formed by two semitransparent media. Localized discrepancies within the thickness of a thin film (top media) contribute to variable interference patterns that produce the colorful array.
question10
Velocity is displacement divided by time, and instantaneous velocity is the slope at a given point on a displacement vs. time graph. The slope of the given graph is zero at points I and III, and therefore the observed frequency at these points is unchanged at 6 × 1014 Hz concept: The frequency f of a wave can be determined from its propagation velocity v and wavelength λ: f = v/λ. If the observed frequency is the same as the source frequency, there is no frequency shift (Doppler effect). On a displacement vs. time graph, the instantaneous velocity is the slope at a given point.
Question 5
concept: Photons are oscillating packets of electromagnetic energy that are characterized by their wavelength and frequency. The frequency of a photon can be calculated from its energy: f = E/h
quesiton8
concept: The distance to an image formed by a converging lens depends on the distance to the object and the focal length of the lens. This is known as the thin lens equation: 1/f = 1/o + 1/i. The ratio of the image height to the object height is equal to the ratio of their respective distances.
question 8
deposition = gas to solid melting = solid to liquid entropy = more disorder so highest during gas then liquid then solid
question 36
higher refraction = lower speed and vise versa concept: Snell's law may be used to predict the relationship between the angle of incidence and angle of refraction provided that the relationship between the refractive index of each medium is known. Light will bend toward the normal when it passes through a media interface from lower to higher refractive index.
question 4
myopia = divergining lens used to lengthen focal length = greater radius hyperopia = converging lens used to shorten focal length = shorter radius A converging (convex) lens converges parallel rays of light toward its focal point. A real image is formed from the convergence of the refracted light rays on the side of the lens opposite the object. Real images are always inverted (upside-down with respect to the object). A diverging (concave) lens spreads parallel rays of light away from its focal point. A virtual image is formed from the apparent convergence of refracted light rays traced back to the same side of the lens as the object. The image is virtual because the light rays do not actually converge at the image. Virtual images are always upright. concept: Myopia is a condition in which light rays from distant objects are focused in front of the retina. Myopia can be corrected using diverging lenses, which spread light rays before they reach the eye. A diverging lens creates upright virtual images.
question7
needed to use the lens strength equation (same as the focal length equation) concept: Lens strength (refractive power) is the inverse of the lens's focal length and is measured in units of diopters (D). A diopter is equal to an inverse meter (m−1). Lens strength can be determined from object distance and image distance using the thin lens equation: S = 1/o + 1/i.
question 9
with the given focal length you have to find the new power and then subtract -4D from it Lens power = 1/focal length concept: The optical power (or strength) of a lens is equal to the inverse of its focal length in meters (S = 1/f). The value is positive for converging lenses and negative for diverging lenses. The combined lens strength of a multi-lens system is approximated as the sum of the strengths of each individual lens.
q22
concept: Electric current is the rate of charge flow and is calculated as charge divided by time: I = Q/t. Voltage is the difference in electric potential between two points, and it drives the movement of electric charges. The voltage across a resistor can be calculated from Ohm law (V = IR).
Question 5
concept: Heat capacity measures the amount of heat required to change the temperature of an object by 1 degree. Specific heat is an object's heat capacity per unit mass. The heat capacity C of an object can be calculated from its mass m and specific heat c (C = mc), or from the amount of heat q for a corresponding change in temperature ΔT: q = mcΔT = CΔT.
Question 7
concept: The amount of heat q gained or lost by an object is the product of its mass m, its specific heat c, and its change in temperature ΔT: q = mcΔT, where specific heat is the amount of heat required to increase a unit mass of a substance by 1°C (or 1 K).
question 3
concept: The internal energy of a system increases when heat is transferred to the system and when work is done on the system(ΔU = Q + W). For a system of gases, the amount of work done is equal to the product of the external pressure and change in volume (W = PΔV). look at your miles down notes
question 19
concept: The period of a wave is the amount of time for one cycle to pass through a fixed point, and it is the reciprocal of frequency: T = 1/f.
q21
concept: The power dissipated by a resistor is released as heat, and is the product of voltage and current: P = IV. Ohm law (V = IR) can be used to determine alternate expressions for electric power in terms of resistance: P=V^2/R=I^2R
q18
conductivity = 1/resistivity Conductivity is the ease with which electrons flow within a material. Because resistivity and conductivity are inversely proportional, replacing the resistor with another that has ¼ the conductivity of the original is equivalent to increasing the resistivity of the resistor by a factor of 4. Given that the resistor is otherwise identical (ie, the same physical dimensions), the resistance of the resistor will also increase by a factor of 4. Ohm's law V=IR so replacing the original resistor with another that has ¼ the conductivity (4 times the resistance and resistivity) of the original will decrease the current traveling through the circuit to ¼ its original value Educational objective: Conductivity is an intensive property that quantifies the ease with which current flows through a material acting as an electric conductor. Conductivity is inversely proportional to resistivity.
q30
had to set the 2 equations from the passage equal to each other and turn the necessary variables into their SI units to find the units of viscosity. concept: The units of one variable in an equation can be determined by rewriting the other variables using their units and solving for the units of the target variable.
question 10
in a calorimetry system, its a close system (thermally insulated) where you measure the temperature. Energy is released as heat if the enthalpy of the products is lower than the enthalpy of the reactants, and ΔH is negative (exothermic). Because the temperature of the surroundings (water) increases in the combustion of the sample, heat is released and therefore ΔH is negative. Because the gaseous products of the reaction are more disordered than the solid powdered sample, disorder increasesand therefore ΔS is positive. Concept: Enthalpy (H) is a measure of bond energy, and a change in the enthalpy of a reaction results in the release or absorption of heat. Entropy (S) is a measure of disorder, and it is highest in gases and lowest in solids due to their respective molecular structures. In the combustion of a solid to a gas, heat is released (ΔH is negative) and the products are more disordered (ΔS is positive).
q26
needed to use the resistance of a resistor equation. Image Concept: The resistance of an object is directly proportional to its resistivity and length but inversely proportional to its cross-sectional area. Resistivity assesses the intrinsic resistance within a defined volume of a material.
question 18
psg said that the crystals produce sound when an alternating voltage is applied to them. So from that we can conclude that the expansion and contraction of the crystals will cause molecules in the surrounding medium to vibrate, creating sound waves concept: Sound is propagated in the form of pressure waves by the vibrations of the molecules in a medium. The rapid expansion and contraction of crystals creates pressure waves (sound) by vibrating nearby particles.
question 12
the amount of heat required to change the temperature of a substance is by using the equation q=mc∆T In the experiment described in the passage, the heat released from the combustion reaction is absorbed by the surrounding water (m = 500 g). The description of a gram calorie (cal) is the definition of water's specific heat: c = 1 cal/(g⋅°C). The maximum temperature change ΔT = 10°C (Figure 1) is due to the total heat released from the combustion reaction. The heat q released in cal is the product of these values q = (500 g)(1cal/g⋅°C)(10°C) = 5 ,000 cal The value of 5,000 cal of heat energy is converted to kJ using the conversion provided in the passage: 1,000 cal = 4.185 kJ ≈ 4.2 kJ (rounded to two significant digits). q=(5,000 cal)(4.2 kJ/1,000 calories) = 21 kJ concept: Calorimetry is a technique used to measure heat transfer from changes in temperature. The specific heat of a substance is the amount of heat required to increase 1 g of a substance by 1°C. The change in heat q is the product of the mass m, the specific heat c, and the change in temperature ΔT: q = mcΔT.
q1
the dielectric of vacuum or air is 1 and thats how you know that 1.5 would be a 50% increase bc 1 + .5 = 1.5 Based on the glucose concentrations given in the q stem, you had to use the passage graph to find the dielectric constant. At 10mM, the dielectric constant is 1.2 and at 2.5mM, the dielectric constant is 1.0. So, then you just had to find the percent difference. Picture of math. Therefore, decreasing the glucose concentration of blood from 10 mM to 2.5 mM will decrease the capacitance of red blood cell membranes blood by approximately 20%. Content: the strength of a capacitor is quantified by its capacitance, which is the ratio of the quantity of stored charge (Q) to the voltage (V) generated by the separated charges: C=Q/V. Dielectrics are polarizable substances that can be inserted between the plates of a parallel plate capacitor to increase its capacitance. The dielectric constant quantifies the ability of a dielectric material to increase capacitance.
question 9
thermal conductivity is like heat conduction so the answer is that tile has a higher thermal conductivity when you step on a tile your body transfers the heat better on to the floor whereas the carpet does that slower
q29
volumetric blood flow is given in passage as "Q" in eqn: P=QR solve for Q that gives you P/R and substitute for R from equation 2 given in passage Q asks which would give you the greatest DECREASE in "Q" so decreasing the radius by factor of 2 would decrease "Q" because its in the denominator so direct relationship and also "Q" decreases by factor of 16 when radius is halved look at eqn on side Educational objective: Poiseuille law is used to model fluid flow in pipes, assuming laminar flow of viscous and incompressible fluids. According to Poiseuille law, the flow rate is directly proportional to vessel radius and pressure difference, and inversely proportional to viscosity and vessel length.
q16
"Electrical potential is differences in voltage that drives the movement of electrical charges. The electromotive force (ℰ) is the energy per unit of charge that is supplied by a battery or other generator to move charge through a circuit. Had to know the equation which is V= e - Ir so increasing the internal resistance of the battery connected to the circuit powering a lightbulb will not change the magnitude of the emf, but will decrease the terminal voltage. Educational objective: The electromotive force quantifies the capacity of electrical generators to establish an electric potential energy gradient. Due to internal resistance within the electrical generator, the observed terminal voltage is less than the electromotive force."
Percentages
"Percent of" - just multiply the number by the percent "Percent changes (increase or decrease) is different: its always 1 + the change
question 6
****remember: increase by 50% is increase by a factor of 1.5 NOT .5 concept: The energy of a photon is proportional to its frequency (E=hf), and its frequency is inversely proportional to its wavelength (λf=c). Therefore, the change in energy of a photon is inversely proportional to its change in wavelength (E=hc/λ).
question 32
A diffraction grate is a diffractive array composed of numerous slits with near-zero width similar to the wavelength of incident light. Like the band patterns produced through single-slit diffraction and double-slit diffraction, dark bands that result from light passing through a diffraction grate are caused by destructive interference between light waves. Conversely, light bands are caused by constructive interference between light waves. Compared to other diffractive phenomena, the band pattern caused by grated diffraction is characterized by relatively sharp and narrow peaks (ie, thin peaks with highly variable amplitude) Concept: Diffraction grating refers to passage of light through an array consisting of numerous slits. Diffraction grating may be used to determine the components of polychromatic (eg, white) light and other mixed electromagnetic wavefronts.
question 11
A linear polarization filter, for example, allows for the transmission of electromagnetic radiation oriented parallel to the axis of polarization but inhibits the passage of radiation oriented perpendicular to this axis. Because only electromagnetic radiation with an electric field oriented parallel to the axis of polarization passes through, the total intensity of light will therefore decrease by 50% when nonpolarized light passes through a linear polarization filter. concept: Linearly polarized waveforms are associated with oscillations that occur in a particular orientation of the x,y,z-coordinate system. A linear polarization filter blocks electric fields aligned perpendicular to the axis of polarization (ie, 50% of total intensity).
question 16
A simple relationship can be used to relate dB changes to relative intensities: a 10-fold increase in intensity is a change of +10 dB; similarly, a 10-fold decrease in intensity is a change of −10 dB. Therefore, a 100-fold decrease in intensity corresponds to a change of (−10) + (−10) = −20 dB. From Figure 1, the 10 MHz and 5 MHz signals are attenuated by 20 dB at a depth of 2 cm and 4 cm, respectively. The difference between the two depths is: 4cm − 2cm = 2cm concept: The decibel (dB) scale is logarithmic and relates the perceived loudness of a sound to its actual intensity. For each 10-fold decrease, sound intensity decreases by 10 dB. Therefore, a 100-fold decrease in sound intensity corresponds to a decrease by 20 dB.
question 26
A sound wave carries energy in the form of longitudinal mechanical waves, and the energy is related to the intensity of the sound wave. When sound crosses from one medium to another, a portion of the wave's energy is reflected. Therefore, sound waves lose energy (are attenuated) and their intensity decreases when passing from air to a solid structure, such as the tympanic membrane. Wave velocity v is the product of wavelength λ and frequency f: v = λf When a wave moves from one medium to another, its frequency does not change. Changes in wave velocity are only due to changes in wavelength. The propagation velocity of sound waves depends on the properties of the medium: Velocity increases with temperature. Velocity is slowest in gases, faster in liquids, and fastest in solids. Within a phase of matter, velocity increases with stiffness and decreases with density. Therefore, when sound passes from air to a solid (such as the tympanic membrane), its propagation velocity increases. concept: Therefore, when sound passes from air to a solid (such as the tympanic membrane), its propagation velocity increases When sound moves from one medium to another, a portion of its energy is reflected, decreasing its intensity. The propagation velocity of sound depends on the medium and is slowest in gases, faster in liquids, and fastest in solids.
question 14
Although standing wave vibrations may take place in any object following perturbation, vibrations that occur in non-acoustic objects are generally inaudible because the amplitude (A) of the vibrations is too small or because the resonance frequency (f0) falls outside the audible range. The high-amplitude vibrations associated with shock wave ultrasound, for example, occur only because the shock wave frequency (f) approaches (or is equal to) the resonance frequency of the target structure. concept: Shock wave therapies like shock wave ultrasound utilize high-frequency waves to cause destructive, high-amplitude vibrations within target structures. For maximum effectiveness, the frequency of the shock waves should match the resonance frequency of the target structure.
question 20
An infrared laser uses a form of electromagnetic radiation (light), which travels at the speed of light c = 3 × 10^8 m/s. The speed of sound in blood is given in the passage as c = 1,570 m/s. Because the speed of light is much greater than the speed of sound, the observed frequency shift will be smaller for laser Doppler flowmetry. concept: The Doppler effect can be approximated by the relative velocity between the source and the observer and the speed of the wave in the medium (∆f/f=v/c) The magnitude of the frequency shift is inversely proportional to the wave's speed. The Doppler effect of light will result in smaller observed frequency shifts because the speed of light is much greater than that of sound.
question 21
Because the crystalline lattice of many materials exceeds the complexity of simple crystals, the pattern of bright spots produced on the photographic film is indicative of a molecule's three-dimensional structure and its packing orientation within the crystal lattice Concept: X-rays diffract within molecules because the space between atoms is comparable to the wavelength of x-rays. X-ray diffraction through a sample of a purified and crystallized material can be used to determine its three-dimensional molecular structure and packing.
question 31
Circular polarization occurs when two wave forms with equal amplitude and perpendicular linear polarization (ie, polarized along different axes) propagate 90° out of phase to one another (ie, one waveform yields zero displacement when the other waveform is yielding a peak or a trough). The mismatch in phase causes each contributing wave to generate momentary oscillations that are different at every point in time. This results in a continuous rotation in the orientation of the combined wave. Concept: Circular polarization refers to the rotation of polarization observed when two transverse waves with equal amplitude and perpendicular linear polarization propagate out of phase with one another by 90°.
question 25
Complete noise cancellation occurs when the generated sound wave destructively interferes with the original wave at all points, resulting in an amplitude of zero. A wave that is flipped across the x-axis will have equal and opposite amplitudes at each point along the wave. The sum of two equal and opposite amplitudes is zero, resulting in total destructive interference and canceling all noise. Concept: Constructive interference occurs when the sum of the amplitudes results in a larger amplitude. Destructive interference occurs when the sum of the amplitudes results in a smaller amplitude. A wave that is combined with a copy of itself that has been flipped across the x-axis would result in complete destructive interference.
question 24
For every increase in 10 dB, the ratio of the intensities increases by a factor of 10 (eg, +20 dB = 102 = 100 times more intense). Conversely, the ratio of the intensities decreases by a factor of 10 for each decrease in 10 dB. From Figure 2, the hearing threshold at 1,500 Hz is 20 dB and the hearing threshold at 2000 Hz is 50 dB. So the relative intesity btw the 2 frequencies is -30dB. A sound that is 30 dB lower is 10^3 = 1,000 times less intense concept: The intensity of sound is measured on a logarithmic scale with units of decibels (dB). For each decrease in 10 dB, the sound intensity decreases by a factor of 10. Therefore, a decrease in 30 dB is equal to a 1,000-fold decrease in intensity.
q9
For this q you can use POE to eliminate choices B and C bc if a plate is positively charge, the electric field line will point away from it, not toward it (making B wrong). Likewise, if the plate is neg then the field line will point toward it (making C wrong). The question is asking for the charge of the plate if positive ions are accelerating away from it. Since, like charges repel, the plate must be positive since the ions are moving away from the plate. If the plate is positive, the electric field lines will point away from it, making A the right answer Concept: Electric charges with the same sign repel, and charges with opposite signs attract. Electric field lines point out from positive charges and into negative charges. Therefore, a positively charged plate repels positively charged ions, and the electric field lines point away from a positively charged plate.
q25
Had to know Capacitance = k(Co) --> dielectric constant equation We also need to know that a vacuum's dielectric constant = 1 so if k becomes 1.5 then it will increase capacitance by 50% Educational objective: A dielectric can be introduced between the plates of a parallel plate capacitor to cause an increase in capacitance. The dielectric constant κ measures the ability of a dielectric material to increase capacitance.
q5
Had to solve it and find the common denominator basically. Math is shown on the picture Content: Resistors are circuit components that deplete electric potential energy by opposing electric current. Placing multiple resistors in series increases the total resistance whereas placing multiple resistors in parallel decreases the total resistance.
q13
Had to use the two centripetal force equations (image) concept: The force exerted on a moving particle in a magnetic field is known as the magnetic Lorentz force, and it is equal to the product of the particle's charge, velocity, and strength of the magnetic field: F = qvB. This force is the centripetal force that curves the path of ions in MS-MS. Therefore, an expression for the radius of curvature can be determined by equating the Lorentz force and centripetal force equations.
q23
If V is fixed in V=IR, a change in R causes an inverse change in I. At 200 Hz, the resistance RC is 400 Ω, and it decreases to 200 Ω at 400 Hz. So, decreasing R to half its value doubles I. (image) Therefore, the current reading on the ammeter will double, or increase by 100%. Concept: An ammeter in series with a circuit component measures the current through that component. Ohm law states that voltage equals the product of current and resistance: V = IR. Because current is inversely proportional to resistance if the voltage is fixed, reducing the resistance by half will double the current.
question 2
Ignoring spherical aberrations, the focal length of a spherical mirror is equal to half the radius of curvature (r) , where r is the distance between the midpoint of the mirror surface and the center of the imaginary sphere of which the mirror surface is only a portion: f = r/2 The equation for focal length is identical for both convex and concave mirrors. Consequently, a concave mirror and a convex mirror with the same radius of curvature will have identical focal length magnitudes. However, the point of focus is positioned in front of a concave mirror and behind a convex mirror For this, all you had to do was 4/2 = 2m for the focal length. concept: Concave (converging) spherical mirrors create real, inverted images of objects placed outside of mirror focal length. The focal length of a concave spherical mirror is half the radius of curvature and is positioned in front of the mirror.
question 23
In other words, the motion of the observer or waveform source relative to each other leads to a shift in only the apparent, perceived velocity of the sound waveform as successive waveform crests and troughs are perceived closer together or farther apart. For example, when the source or observer is moving away from the other, the distance between successive waveforms increases and the perceived waveform velocity decreases. My answer was wrong bc the decay in sound wave intensity that occurs as the distance btw the source and the observer is unrelated to the motion of the source and the observer. It doesn't explain the frequency shifts associated with the droppler effect concept: The Doppler effect describes apparent changes in the velocity of waveforms that lead to changes in the observed frequency of those waveforms, which are known as Doppler shifts; however, the actual velocity of waveforms does not change when Doppler shifts occur.
q3
In series, whoever has the most resistant will have the most voltage drop. Voltage drop is proportional to each R. In parallel, the voltage drop across all resistors are equal. In the the passage the circuit shown is a parallel circuit so the voltage drop is equal. Resistors in parallel increase current because the electrons have another path to go to. Current splits across resistors in parallel but has to equal total current. Current stays the same across resistors in series and is the same as total current. Content: Circuit components may be placed in series (positioned successively) or in parallel (positioned side by side). For resistors in parallel, the voltage drop across each resistor is identical. For resistors in series, the current passing through each resistor is identical.
q32
In the study described in the passage, different blood vessels of rats (independent variable) were accessed through an invasive laparotomy procedure (suspected confounding variable) to measure mesenteric blood pressures (dependent variable). The inclusion of an alternative procedure that is minimally invasive or noninvasive but still measures mesenteric blood pressures would determine if laparotomy is a confounding variable by determining if differences are found in the measured blood pressures. concept: A confounding variable is an uncontrolled variable different from the independent variable but that still has an impact on the dependent variable. The effect of a confounding variable can be observed by including a group that differs in the confounding variable.
question 15
Isolated system = don't exchange energy or matter Closed = exchange energy but not matter In the passage they say "The bomb cell was submerged in 500 g of water at room temperature (25°C) in an enclosed and thermally insulated calorimetry device." Since the bomb cell was submerged in water, it would be exchanging heat with its surrounding (water) and the calorimetry device is insulated meaning that no heat is being exchanged so that has to be an isolated system. Concept: An open system allows heat and matter to be exchanged with the surroundings. A closed system allows heat but not matter to be exchanged with the surroundings. An isolated system does not allow heat or matter to be exchanged with the surroundings.
question 9
It says in the psg that gamma rays lose energy during Compton scattering because energy is transferred from the photon to the electron. Therefore, the scattered photon frequency should be lower than the incident photon frequency because its energy has decreased (Number I) If Compton scattering occurs in the patient, the trajectory of the scattered gamma ray will be altered. So the calculated point of origin will be different from the actual location (Number II). concept: The energy of a photon is proportional to its frequency: E = hf. Therefore, a photon's frequency will decrease as its energy decreases. The velocity of a photon's propagation is independent of the photon energy.
question 13
Its bc they say sublimation and talks about collecting cooled condensation concept: The phases of matter describe the physical state of the matter's molecules, and include solid, liquid, and gas. Sublimation is the phase change from solid to gas, and condensation is the phase change from gas to liquid.
q4
Knew how to do it but did the math wrong content: Resistance describes an object's opposition to the flow of electric charge (ie, current). The resistance of an object is directly proportional to its resistivity and length but inversely proportional to its cross-sectional area.
question 30
Light rays approaching equally smooth interfaces at different angles of incidence will reflect away from each interface at different angles of reflection. Therefore, light rays that approach a smooth interface at an angle of 12° (high refractive index condition) will reflect away from the interface at half the angle of light rays approaching the interface at an angle of 24° (low refractive index condition) concept: Light reflects from an interface between media and travels in a new direction within the original medium. For smooth media interfaces, the angle of reflection is equal to the angle of incidence.
question 8
Looked at table 1 and saw that choice A had the highest index of refraction. The higher the refraction, the slower the speed and thats why A is the right ans concept: Light travels fastest in vacuum and it slower in transparent materials. The ratio of the speed of light in a vacuum c to the speed of light in a material v is the material's index of refraction (n=cvn=cv). Therefore, the higher the index of refraction, the slower light travels through a material.
Q4
Magnetic field lines go from North to South Magnetic fields are created by moving charges thats why C is correct bc its the only choice talking about any motion Fm= qvB and so if the velocity is zero then there is no force concept: Magnetic fields are generated by electromagnetic radiation, permanent magnets, or the motion of charged particles. The direction of magnetic fields generated by moving charges can be determined using the right-hand rule.
question 13
Multiple standing waves in pipes develop in a fixed series known as harmonics. The first harmonic (fundamental frequency) is the longest wavelength that may be produced within a pipe. The 1st harmonic has the most intense standing wave. As the harmonics get higher, they have smaller wavelengths and higher frequencies than those of the 1st harmonic For a pipe closed at one end, the wavelength of each harmonic is proportional to object length (L) and harmonic number (n = 1, 3, 5...): λn = 4L/n They say the length is 1.5 and its in 3rd harmonic so the equation will be λ3 = 4(1.5)/3 Standing waves can be elicited within open and closed pipes. There are no even-numbered harmonics in the harmonic series of a pipe closed at one end because the closed end of a pipe is always a node and the open end is always an antinode.
question 14
Need to understand that ice melts because it absorbs heat. Temperature ON LY increases after ALL the ice is melted. The heat released from the combustion reaction will first go toward the latent heat of fusion to melt the ice into liquid water. The temperature of the water will be constant at 0°C as long as ice is still present and will not start to increase until after all the ice melts. The latent heat of fusion (melting) is the amount of heat (energy) required to convert a solid at its melting point temperature to its liquid phase by breaking the bonds between the molecules in the solid phase. Therefore, the temperature of the water would begin to increase at a later time (compared to the original experiment) when enough heat is transferred from the combustion reaction to first melt the ice (latent heat of fusion). Concept: The phase transition from a solid to a liquid requires heat (energy) to break the bonds between molecules; this energy is the latent heat of fusion. When heat is added to a mixture of ice and water at 0°C, the heat will first go toward melting the ice before raising the temperature of the water.
q6
Need to understand that metals like sodium are good conductors. The conductance of an electric conductor is directly proportional to its conductivity. Conductivity is inversely proportional to resistivity. Here since you are adding sodium ions, you are basically increasing the electric charge of the blood and the conductivity is increasing meaning resistivity is decreasing. Since resistivity is proportional to resistance, resistance is also decreasing. Current is inversely proportional to resistance and thats why current is increasing. Since the resistivity of blood decreases while conductivity increases, the electric current increases with greater dietary sodium intake. concept: Conductivity describes the ease with which electric current flows through a material. The conductivity of metals may be attributed to the loosely associated valence electrons within a metal whereas the conductivity of electrolytic solutions is directly proportional to the molar concentration of charged ions.
q27
Needed to use coulombs law where F is inversely proportional to r^2. The electric force generated by two charges separated by Distance A is 4 times greater than the electric force generated at Distance B. Stated differently, moving from Distance A to Distance B decreases the electric force by a factor of 4. According to Coulomb's law, this relationship would be observed when Distance A is shorter than Distance B by a factor of 2. concept: Coulomb's law may be used to determine the electric force generated by two point charges separated by some distance. Electric force is inversely proportional to the square of the distance separating the two charges.
q15
Needed to use the C=Q/V equation the q is asking to find charge (q) and they gave the capacitance = 8 farads and V = 5 volts FARAD IS THE UNIT FOR CAPACITANCE!!! concept: Capacitors generate electric potential (voltage) by storing charge. The quantity of charge stored by a capacitor is a product of capacitance (capacitor strength) and the voltage generated by charge storage.
q12
Needed to use the equation E = F/q but also had to double the charge bc in the question they say that its a doubly ionized particle concept: The force exerted on a particle in a uniform electric field is the product of its charge and the magnitude of the electric field: F = qE.
q19
Needed to use the equation for the energy of a charged capacitor: U = 1/2CV^2 The passage gives us the capacitance as 2 μF and the q stem gives the voltage as 50mV concept: Capacitance is the ability of a capacitor to store electric charges. The amount of energy U stored in a charged capacitor depends on its capacitance C and the voltage V across its plates: U=12CV^2
oscillations of the electric and magnetic field
Only electromagnetic radiation with an electric field oriented parallel to the axis of polarization passes through, Light waves with magnetic fields oriented perpendicular to the axis of polarization have electric fields parallel to the axis of polarization. Such waves are transmitted through the polarizer and are not absorbed.
q10
Passage talked abt two diff types of mass spec: TOF-MS and MS-MS. TOF-MS: used to separate ions by the amount of time taken for the ions to travel a fixed distance, no electrical or magnetic field. The time it takes for an ion to reach the detector depends on its m/q ratio MS-MS: Has a magnetic field which bends ions trajectories into curved paths. Radius of curvature depends on ion's m/q ratio. Ion Y in q stem took more time to reach detector in TOF-MS which means it has greater m/q ratio than ion X which has a lower m/q ratio. In MS-MS, ions of higher mass and lower charge are less affected by the magnetic field and have a larger radius of curvature. Therefore, the radius of curvature is directly proportional to the m/q ratio. As a result, the ion with a lower m/q ratio, ion X, will be observed to have a smaller radius of curvature. B is incorrect bc ion Y has a higher m/q ratio, it is less affected by the magnetic field and has a larger radius of curvature. concept: Ions in TOF-MS are separated by their travel time to the detector, which is proportional to its m/q ratio. Ions in MS-MS are separated by their radius of curvature, which is directly proportional to its m/q ratio. Therefore, an ion that takes less time to reach the detector in TOF-MS has a small m/q ratio and a smaller radius of curvature in MS-MS.
question 12
Phase difference (or phase shift) refers to the degree to which the cyclical nature of two equal-frequency waveforms are aligned. For example, a phase difference of 0° indicates that both wave functions are fully overlaid and reach minimum or maximum displacement together at the same point in the waveform cycle. Conversely, a phase difference of 180° (half a cycle) indicates that the maximum of one wave function occurs concurrent to the minimum of the other waveform. As a result, phase difference expresses the degree of constructive and destructive interference between two waveforms. In this question, waveforms A and B are out of phase by 180°. Therefore, when waveform A reaches its maximum displacement (+100 m) waveform B reaches its minimum displacement (-100 m). The expression for total displacement caused by two interfering waveforms is the sum of the individual relative displacements (y-axis values) of each waveform: Total displacement = Waveform A displacement + Waveform B displacement Total displacement = (100 m + -100 m) = 0 m concept: Phase difference relates the alignment of two equal-frequency waveforms to one another. Phase differences can result in constructive interference, destructive interference, or no interference.
q31
Q is asking which of the following blood vessels has the greatest total vascular resistance during systole? Vascular resistance equation is given in passage as ΔP=QR so rearrange for R gives you R=ΔP/Q so R is directly proportional to the pressure diff. Since Q is the same for each vessel, R is only dependent on ΔP. So the vessel with the greatest ΔP has the greatest R. All pressure measurements in the study were recorded during systole, the point of greatest pressure. Therefore, the pressure drop across a vessel is the difference between its pressure and the pressure of the next vessel. These pressure differences are calculated from Figure 2. The arterial arcade has the greatest pressure difference of 61 mm Hg, and therefore has the greatest flow resistance. Educational objective: The vascular resistance of a vessel is directly proportional to pressure difference and inversely proportional to volumetric flow rate. When the volumetric blood flow rate is the same in two vessels, the vessel with the greater pressure difference has the greater resistance to flow.
question 22
Refractive errors are caused by a mismatch between the physical dimensions (eg, length) and optical properties of the eye. For example, hyperopia (ie, farsightedness) is a condition that results when the optical power (S) of the eye is insufficient to refract light rays from nearby objects. A hyperopic eye cannot sufficiently refract light rays that approach the eye at an angle (eg, light rays from nearby objects), producing an image of nearby objects that is sharpest at a location behind the retina. Hyperopia is corrected by placing a converging lens in front of the eye, forming an optical system with greater optical power. Consequently, images of nearby objects shift closer to the lens and onto the retina after a corrective lens is placed in front of the hyperopic eye. concept: Hyperopia describes the refractive error that results in an individual being unable to see nearby objects. Hyperopia is caused by the optical power of the eye being insufficient relative to the length of the eye; the condition is corrected by placing a converging lens in front of the eye.
q24
Resistors in series are additive (RAS). The question is asking how would you find the resistance if two resistors are being added to another resister is series. Basically, you have 3 resistors in total and since they are additive, you can find the resistance by multiplying by 3. concept: Circuit components in series are connected end to end and share the same current. The equivalent resistance of resistors in series is the sum of the individual resistances.
Transverse vs longitudinal waves
Sound is transverse
question 15
Sound propagates through the vibrations of the molecules as longitudinal pressure waves, and therefore cannot exist in a vacuum. Attenuation (damping) is the decrease in the amplitude (intensity) of a wave due to absorption and scattering. The attenuation of sound is greatest in soft materials and increases with distance. Sound travels most slowly in gases and most quickly in solids. Sound is attenuated as a function of distance traveled by the inverse square law
question 4
Spherical aberration describes the phenomenon by which real lenses' perfectly rounded (ie, spherical) surfaces do not produce an image at a single point, but rather at a series of focal points. Spherical aberration is most pronounced among rays entering and exiting the lens periphery (ie, distant from the principal axis). Furthermore, correcting spherical aberration in converging lenses requires using an aspherical lens in which the thickness of the lens periphery is decreased relative to a perfectly rounded lens. Because reducing the thickness of the lens periphery will lead to less refraction of light, light rays exiting the periphery of a spherical converging lens can be said to refract excessively, converging on a focal point that is too close to the lens. concept: Spherical aberration occurs when lenses with perfectly rounded surfaces focus light at multiple focal points. Spherical aberration is most pronounced among light rays entering and exiting the periphery of converging lenses.
Question 1
State functions describe the equilibrium state of a system as a relationship between various thermodynamic variables and are independent of the path taken by the system to arrive at its present state. Process functions describe the path taken by a system to transition from one equilibrium state to another. A system transitions from one state to another due to a net flow of energy in the form of heat transfer or work. For example, the loss or gain of heat is a process function because it describes the path taken by a system from its current pressure, volume, and temperature to a different set of values. Only 2 process functions are work and heat Concept: State functions describe the equilibrium state of a system as a relationship between various thermodynamic variables, and a process function describes the path taken by the system to go from one equilibrium state to another. Therefore, entropy is a state function, and work is a process function
q20
The circuit given in the passage shows that the capacitance and the resistor are in parallel. So, you have to find the voltage in that capacitor and the voltage in parallel stays the same so you can use the voltage to find the current through Rm. First, you have to find the voltage thru Cm using V=IR (graph gives you a resistance of 400 ohms and the current is given as .7A). Voltage comes out to be 280. You can use that voltage to find the current in Rm. The resistance of Rm (200 ohms) is given in the passage. concept: Circuit components in parallel have the same voltage across them. The current through a resistor can be determined from its resistance and the voltage across it using Ohm law: V = IR.
q34
The circuit shown in the passage is in parallel. The properties of parallel resistors: 1) The voltage drop across each resistor is the same. If they are in parallel with the battery, the voltage drop across each resistor will be equal to that of the voltage generated by the battery. 2) The equivalent resistance decreases if a resistor is added in parallel. Conversely, the equivalent resistance increases if a resistor in parallel is removed. 3) The current through each resistor is independent from that through the other resistors. The total current is equal to the sum of the currents through each component. So, here the total vascular resistance will increase with the removal of. a resistor (brain) because its one of the properties of parallel resistors concept: For resistors in parallel, the voltage drop across each resistor is the same. The equivalent resistance increases if a resistor is removed. The current through each resistor in parallel is independent from the others, and the sum of each component current equals the total current.
Question 4
The dry Ice wouldn't lose heat it would gain heat. Conduction is the transfer of heat through direct physical contact. Convection is the transfer of heat through the flow of fluids. Fluids absorb heat from hotter regions and deliver it to colder regions. Radiation is the transfer of heat through electromagnetic radiation, such as infrared light. Radiation heat transfer is significant only for high temperatures. Concept: Heat is energy that flows from high temperatures to low temperatures. Heat can be transferred through direct physical contact (conduction), through the flow of fluids (convection), or through emission of electromagnetic energy (radiation).
question 1
The ejection of an electron from a surface by incident electromagnetic radiation depends on the frequency of incident electromagnetic radiation. The energy absorbed by an electron must contribute to either the ejection of the electron (overcoming the work function) or to the kinetic energy of the electron following ejection: hf = 1/2mv^2 + W concept: The photoelectric effect describes the ejection of electrons from a substance due to the absorption of electromagnetic radiation with sufficient energy. Because the energy needed to eject an electron is fixed via its work function, increasing the energy of electromagnetic radiation will increase the kinetic energy of ejected electrons.
question 27
The frequency of a sound is associated with its perceived pitch (or tone). A sound with a high frequency is perceived to have a high pitch, and a sound with a low frequency (such as those near the apex) is perceived to have a low pitch. concept: The frequency of a sound is associated with its perceived pitch; high-frequency sounds have high pitches. The low-frequency sounds that cause resonance near the apex of the basilar membrane are characterized by low pitches.
question 7
The intensity of electromagnetic radiation is proportional to the individual energy of each emitted particle and the number of particles emitted per unit time. According to the passage, each positron produces two gamma rays when it annihilates with a nearby electron. Increasing the rate of positron emissions will increase the number of gamma rays produced per unit time, and therefore increase the intensity of gamma rays. concept: Intensity measures the amount of power (energy per unit time) delivered per unit area. The intensity of electromagnetic radiation increases with higher individual photon energy and higher emission rate.
q33
The pressure exerted by the weight (potential energy) of a fluid is directly proportional to its depth. This pressure is known as hydrostatic pressure. The hydrostatic pressure difference ΔP between any two points in a fluid is found by ΔP = ρgΔh where ρ is the density of the fluid, g is the acceleration due to gravity, and Δh is the vertical displacement between the locations where the initial and final pressures are measured. When the person is lying down, the neck and the leg are at about the same height level, making Δh negligible. However, when the person stands up, the Δh between the neck and the leg increases significantly. The blood pressure difference increases due to the hydrostatic pressure of the column of blood from above the leg to below the neck. concept: Hydrostatic pressure is the pressure exerted by the weight (potential energy) of a fluid. The hydrostatic pressure difference between two points in a fluid is proportional to the fluid's density, the gravitational acceleration, and the vertical displacement between the two points.
q8
The q is asking how can you stop accidental fires meaning what can you use to stop current. Out of the 4 choices, A and C can be eliminated because conductors conduct current and electricity but we are trying to do the opposite here in the question. Electrical fires begin as combustible foreign materials enter the electrical circuit, accumulate thermal energy from the high voltage source, and ignite. To prevent such accidental fires, electrical wires are coated in with an electrical insulator with high resistance, which does not transmit electrical energy and prevents electric current from easily exiting the circuit. D is wrong bc thermal insulators are used to maintain temperature of a region or object not to stop electrical accidents. concept: Electrical conductors facilitate electrical current (ie, the movement of charge) whereas electrical insulators inhibit current. Although some electrical conductors are also thermal conductors, mechanisms of thermal and electrical conductivity are not the same.
Q3
The q is saying that a proton in this magnetic field is following path A so what would happen to an electron in this magnetic field Have to use the equation F= qvB where the force is perpendicular to the velocity and thats why the trajectory is curved. Similarly to electric fields, positive and negative charges move the opposite direction. So, if the positive charge is moving left, the negative charge must move right. Electrons have smaller charge so it would be D instead of B concept: The Lorentz force exerted on a moving charge in the presence of a magnetic field is perpendicular to the particle's velocity. As a result, the charge's trajectory is forced into a curved path, with negative charges and positive charges bent in opposite directions. Because an electron is less massive than a proton, an electron's path would be more curved in the same magnetic field.
q2
The question is simply saying that the capacitance is being increased 250% of its original value. Increase of 250% basically means that its increasing 2.5 times its original value (250/100). Since the area is directly proportional to the capacitance, increasing the capacitance by 2.5x will also need the area (quantity) to be increased by 2.5x which is 5/2. Content: Capacitors store electrical charge on two equally but oppositely charged regions separated by some distance (d). The capacitance of a parallel plate capacitor is related to capacitor plate material, capacitor plate area, and the distance between plates. Capacitance is directly proportional to capacitor plate area and inversely proportional to the distance between plates (C∝A/d).
question 6
The question states that nitrogen gas is cooled past its condensation point; heat is being taken away from nitrogen. Therefore, the temperature of nitrogen initially decreases until it reaches the condensation point. At the condensation point, temperature remains constant because the removal of heat causes the gas to condense into liquid. The temperature decreases again after all the nitrogen has completed the phase change. Concept: Matter exists in three main phases: solid, liquid, and gas. During a phase transition, the temperature of a substance remains constant. The condensation point is the temperature at which the phase transition from gas to liquid occurs, releasing heat equal to its latent heat of vaporization
q7
The sign (+ or -) and quantity of electric charge influences the way charged particles interact. Likes repel and opposites attract. In this question, each of the four charges fixed along the line experiences an electric force from the other three nearby charges. Particle B experiences 3 forces: a repulsive electric force from partcile A (Fab) attractive electric force from both particles C and D (Fbc) and (Fbd). Each of the forces acting on particle B is oriented along the same line toward particles C and D (ie, to the right). Furthermore, FAB has the largest magnitude in this setup because the charges of particles A and B (+4q and +3q, respectively) are relatively large and the distance between particles A and B (rAB) is relatively small. Therefore, the sum of electric forces acting on particle B is the largest in magnitude and will cause B to accelerate most rapidly once charges are released Educational objective: The magnitude and direction of the attractive or repulsive forces exerted between electric charges are directly proportional to the charge of each particle but inversely proportional to the square of the distance separating the charges. Like charges repel - Force is positive opposite charges attract - Force is negative
Q2
To find the Ceq of the whole circuit you first had to find the Ceq of the parallel Capacitors (Capacitors in parallel are additive) so Ceq=2+2=4uF so then adding a C in series is inverse so you get Ceq= 1/4 + 1/4 = 2 Therefore the equivalent capacitance decreased to 2uF from 4uF giving a new to original ratio of 1:2 Educational objective: For capacitors in parallel, the equivalent capacitance is the sum of the individual capacitances: Cparallel=C1+C2+C3... For capacitors in series, the inverse of the equivalent capacitance is the sum of the inverses of the individual capacitances: 1/Cseries=1/C1+1/C2+1/C3+...
question 10
Visible light = 400 to 750 table 1 shows that choice D crystal has a emission wavelength of 320nm so that is outside the visible spectrum concept: The visible light spectrum is the part of the electromagnetic spectrum that the human eye can detect. Visible light has a wavelength between 400 and 750 nm.
question 17
When blood is flowing toward the device, flow velocity (vB) is negative (ie, subtracted from waveform velocity) and the frequency shift is positive (ie, observed frequency > original frequency). A positive frequency shift occurs because each successive wave is reflected closer to the device. Conversely, when blood is flowing away from the device, flow velocity is positive (ie, added to waveform velocity) and the frequency shift is negative (ie, observed frequency < original frequency). A negative frequency shift occurs because each successive wave is reflected farther from the device. concept: The Doppler effect occurs when the observed frequency and wavelength of a sound are shifted from those of the original due to relative motion between the source and the observer. The frequency shift is positive when the source velocity is negative (moving closer) and negative when the source velocity is positive (moving away).
question 28
When the sound source moves toward the observer (subject), the source generates each wave front at a location successively closer to the observer, shortening the observed wavelength. Because the propagation velocity is unchanged, the observer detects each wave at an increased frequency (rate) compared to the source frequency. The inverse relationship between frequency and wavelength can also be explained from the wave velocity equation (v = λf). Concept: When relative motion exists between a sound source and an observer, the observed frequency and wavelength differ from that of the original frequency and wavelength. This phenomenon is known as the Doppler effect. When the source moves toward the observer, the observed wavelength decreases and the observed frequency increases.
question 11
You have to use the graph and the linear expansion equation. The change in the height of the liquid ΔL is 2 mm after the first 2 mins which corresponds to a temperature change (ΔT) of 2 degree C. αL = ∆L/∆T = 2 mm/2°C = 1 mm°C So that means that the height of the liquid increases by 1 mm for every 1 degree C. So, at 4 deg that means the temperature will be 10 degrees. ∆L= (1mm°C)(∆T) ∆L = (1mm°C)(10°C) = 10 mm after 4 mins concept: The expansion of a substance is linearly proportional to its change in temperature, and it is described by its coefficient of thermal expansion. Given a change in temperature and its corresponding change in length, the linear relationship can be applied to predict the change in length at other temperatures.
q17
concept: Circuits composed of multiple loops contain junctions, points on the circuit at which three or more elements meet. The current entering any junction must be equal to the current exiting the junction.