Physics 2 final review
An electromagnetic wave is traveling straight down toward the center of the Earth. At a certain moment in time the electric field points west. In which direction does the magnetic field point at this moment? (a) North (b) South (c) East (e) West (d) Up (f) Down (g) Either (a) or (b) (h) Either (c) or (d) (i) Either (e) or (f).
(a) North
Learning Goal: To understand how to calculate capacitance, voltage, and charge for a combination of capacitors connected in series. Consider the combination of capacitors shown in the figure.(Figure 1) Three capacitors are connected to each other in series, and then to the battery. The values of the capacitances are C, 2C, and 3C, and the applied voltage is ΔV. Initially, all of the capacitors are completely discharged; after the battery is connected, the charge on plate 1 is Q. What are the charges on plates 3 and 6? +Q and +Q −Q and −Q +Q and −Q −Q and +Q 0 and +Q 0 and −Q
+Q and −Q
Assume that the applied magnetic field of size 0.55 TT in (Figure 1) is rotated so that it points horizontally due south. What is the size of the magnetic force on the wire due to the applied magnetic field now? Express your answer in newtons to two significant figures.
0 N
A 10-V, 1.0-A dc current is run through a step-up transformer that has 10 turns on the input side and 20 turns on the output side. 10 V, 1 A 20 V, 1 A 10 V, 0.5 A 20 V, 0.5 A 0 V, 0 A
0 V, 0 A
When switch S in the figure is open, the voltmeter V of the battery reads 3.07 V . When the switch is closed, the voltmeter reading drops to 3.00 V , and the ammeter A reads 1.60 A . Assume that the two meters are ideal, so they do not affect the circuit. (Figure 1) Find the internal resistance r of the battery. Express your answer in ohms to four significant digits. Vt=E-Ir -----> r=(E-Vt)/I r=(3.07V-3.00v)/1.60A=
0.0438 ohms
A pi meson has a mass of 139 MeV/c2. What is this in atomic mass units? m=m/931.49 MeV/c^2 -----> 139MeV/c^2/931.49 MeV/c^2 = 0.15 u
0.15 u
How much sooner? Assume that the microphone is a few centimeters from the singer and the temperature is 20∘C (speed of sound is 343 m/s). tsound-tradio= (53.3m/343/ms)-(1200x10^3/3x10^8)
0.152 s
Learning Goal: To understand the role of the internal resistance of various devices and the use of the ammeter and the voltmeter. Consider the circuit shown.(Figure 1) All wires are considered ideal; that is, they have zero resistance. We will assume for now that all other elements of the circuit are ideal, too: The value of resistance R is a constant, the internal resistances of the battery (r) and the ammeter (RA) are zero, and the internal resistance of the voltmeter (RV) is infinitely large. The voltmeter, as can be seen in the figure, is connected to points 1 and 3. What are the respective voltage differences between points 1 and 2 and between points 2 and 3? 0;E 0;−E E;0 E;E
0;E
A battery provides a voltage of 8.00 V and has unknown internal resistance Rint. When the battery is connected across a resistor of resistance R1 = 7.00 Ω , the current in the circuit is I1 = 1.00 A . (Figure 1) If the external resistance is then changed to R2= 5.00 Ω , what is the value of the current I2 in the circuit? Express your answer numerically in amperes. 8V/1.00A=8ohm Rt=Ri+R1 8ohm=Ri+7.00ohms Ri=1.00 ohms 8.0V/(1.00ohms+5.00 ohms) 8.00/6.00
1.33A
When switch S in the figure is open, the voltmeter V of the battery reads 3.07 V . When the switch is closed, the voltmeter reading drops to 3.00 V , and the ammeter A reads 1.60 A . Assume that the two meters are ideal, so they do not affect the circuit. (Figure 1) Find the circuit resistance R. Express your answer in ohms to three significant digits. I=E/(R+r) -----> R+r=E/I -----> R=(E/I)-r R=(3.07V/1.60A)-0.04375 ohms
1.88 ohms
Learning Goal: To understand how to calculate capacitance, voltage, and charge for a combination of capacitors connected in series. Consider the combination of capacitors shown in the figure.(Figure 1) Three capacitors are connected to each other in series, and then to the battery. The values of the capacitances are C, 2C, and 3C, and the applied voltage is ΔV. Initially, all of the capacitors are completely discharged; after the battery is connected, the charge on plate 1 is Q. f the voltage across the first capacitor (the one with capacitance C) is ΔV1, then what are the voltages across the second and third capacitors? 2ΔV1 and 3ΔV1 1/2ΔV1 and 1/3ΔV1 ΔV1 and ΔV1 0 and ΔV1
1/2ΔV1 and 1/3ΔV1
Two resistors of resistance R5 = 3.00 Ω and R6 = 3.00 Ω are added to the network, and an additional resistor of resistance R7 = 3.00 Ω is connected by a switch, as shown in the diagram..(Figure 2) Find the equivalent resistance RB of the new resistor network when the switch is open. R345=1+7+3=11 ohms R16=R1+R6=2+3=5 ohms R216=(R2*R16)/(R2+R16)= (5*5)/(5+5)=2.5 ohms RB=R216+R345=2.5+11
13.5 ohms
The 7/3Li nucleus has an excited state 0.48 MeV above the ground state. What wavelength gamma photon is emitted when the nucleus decays from the excited state to the ground state? E=hc/lambda lambda=hc/E (6.626x10^-34 * 3x10^8)/7.7x10^-14= 2.58x10^-12m E=0.48x10^6eV(1.6x10^-19 J/eV)=7.7x10^-14
2.58x10^-12 m
An ammeter is connected in series to a battery of voltage Vb and a resistor of unknown resistance Ru (Figure 1). The ammeter reads a current I0. Next, a resistor of unknown resistance Rr is connected in series to the ammeter, and the ammeter's reading drops to I1. Finally, a second resistor, also of resistance Rr, is connected in series as well. Now the ammeter reads I2. If I1/I0=4/5�, find I2/I0. Express the ratio I2/I0 numerically. Rurr=Ru+Rr+Rr Rurr=Ru+2Rr Rurr=Ru+2(Rr/4) Rurr=(3/2)Ru Vb=I2((3/2)Ru) Vb/Ru=(3/2)I2 I0=(3/2)I2 I2/I0=
2/3
A single resistor is wired to a battery as shown in (Figure 1) below. Define the total power dissipated by this circuit as P0. The second resistor is now removed from the circuit and rewired in parallel with the original resistor as shown in the schematic to the left(Figure 3) What is the power, in terms of P0, dissipated by this circuit? Express your answer in terms of P0.
2P0
Learning Goal: To understand how to calculate capacitance, voltage, and charge for a parallel combination of capacitors. Frequently, several capacitors are connected together to form a collection of capacitors. We may be interested in determining the overall capacitance of such a collection. The simplest configuration to analyze involves capacitors connected in series or in parallel. More complicated setups can often (though not always!) be treated by combining the rules for these two cases. Consider the example of a parallel combination of capacitors: Three capacitors are connected to each other and to a battery as shown in the figure.(Figure 1) The individual capacitances are C, 2C, and 3C, and the battery's voltage is V. If the charge of the first capacitor (the one with capacitance C) is Q, then what are the charges of the second and third capacitors? 2Q and 3Q Q2 and Q3 Q and Q 0 and 0
2Q and 3Q
Estimate the total binding energy for 63/29Cu, using the figure. Express your answer to two significant figures and include the appropriate units. 8.8MeV(from figure) * 63 nucleons =554.4 ---> 550 MeV
550 MeV
Learning Goal: We may be interested in determining the overall capacitance of such a collection. The simplest configuration to analyze involves capacitors connected in series or in parallel. More complicated setups can often (though not always!) be treated by combining the rules for these two cases. Consider the example of a parallel combination of capacitors: Three capacitors are connected to each other and to a battery as shown in the figure.(Figure 1) The individual capacitances are C, 2C, and 3C, and the battery's voltage is V. Suppose we consider the system of the three capacitors as a single "equivalent" capacitor. Given the charges of the three individual capacitors calculated in the previous part, find the total charge Qtot for this equivalent capacitor. capacitor c: Q=Cv Capacitor 2c: Q=2CV Capacitor 3c: Q=3CV Qtot: add them together
6 CV
What is the energy of photons (joules) emitted by an 93.3-MHz FM radio station? Express your answer using three significant figures. E=6.626x10^-34 * (93.3 x 10^6)=
6.18 x 10^-26 J
Learning Goal: To understand how to calculate capacitance, voltage, and charge for a combination of capacitors connected in series. Consider the combination of capacitors shown in the figure.(Figure 1) Three capacitors are connected to each other in series, and then to the battery. The values of the capacitances are C, 2C, and 3C, and the applied voltage is ΔV. Initially, all of the capacitors are completely discharged; after the battery is connected, the charge on plate 1 is Q. Using the value of Q just calculated, find the equivalent capacitance Ceq for this combination of capacitors in series. Express your answer in terms of C. Q=CΔV1---> C * 6/11ΔV Ceq=Q/ΔV-----> (C*6/11ΔV)/ΔV
6/11 C
Learning Goal: To understand how to calculate capacitance, voltage, and charge for a combination of capacitors connected in series. Consider the combination of capacitors shown in the figure.(Figure 1) Three capacitors are connected to each other in series, and then to the battery. The values of the capacitances are C, 2C, and 3C, and the applied voltage is ΔV. Initially, all of the capacitors are completely discharged; after the battery is connected, the charge on plate 1 is Q. Find the voltage ΔV1 across the first capacitor. Express your answer in terms of ΔV. ΔV1+ΔV2+ΔV3=ΔV Q/C+Q/2C+Q/3C=ΔV Q/C)1/1+1/2+1/3)=ΔV Q/C(11/6)=ΔV
6/11 ΔV
Carbon dating is useful only for determining the age of objects less than about _____ years old. 1.2 million 600,000 4.5 million 6000 60,000
60,000
Learning Goal: We may be interested in determining the overall capacitance of such a collection. The simplest configuration to analyze involves capacitors connected in series or in parallel. More complicated setups can often (though not always!) be treated by combining the rules for these two cases. Consider the example of a parallel combination of capacitors: Three capacitors are connected to each other and to a battery as shown in the figure.(Figure 1) The individual capacitances are C, 2C, and 3C, and the battery's voltage is V. Using the value of Qtot, find the equivalent capacitance Ceq for this combination of capacitors. Express your answer in terms of C. Ceq=Qtot/V Ceq=6CV/V Ceq=
6C
Two resistors of resistance R5 = 3.00 Ω and R6 = 3.00 Ω are added to the network, and an additional resistor of resistance R7 = 3.00 Ω is connected by a switch, as shown in the diagram..(Figure 2) Find the equivalent resistance RB of the new resistor network when the switch is open. R47=(R4*R7)/(R4+R7)=(7*3)/(7+3)= 2.1 ohms R7 parallel to R4 when closed R3457=1+3+2.1=6.1 ohms RC=R216+R3457=2.5+6.1
8.6 ohms
Consider the network of four resistors shown in the diagram, where R1= 2.00 Ω , R2 = 5.00 Ω , R3 = 1.00 Ω , and R4 = 7.00 Ω . The resistors are connected to a constant voltage of magnitude V. (Figure 1) Find the equivalent resistance RA of the resistor network. Express your answer in ohms. R3+R4=series R34=R3+R4=1+7=8 ohms R1+R2=parallel 1/R12=1/R1+R/2 R12=(R1R2)/(R1+R2) ------>R12=(2*5)/2+5= 10/7 ohms Ra=R12+R34 Ra=(10/7)+ 8
9.4 ohms
If all else is the same, for which surface would the radiation pressure from light be the greatest? A black surface A gray surface A yellow surface A white surface All experience the same radiation pressure, because they are exposed to the same light.
A white surface
Which of the following types of electromagnetic radiation travels the fastest? X-rays Radio waves Visible light waves Gamma rays All the above travel at the same speed.
All the above travel at the same speed
You want to create a spotlight that will shine a bright beam of light with all of the light rays parallel to each other. You have a large concave spherical mirror and a small lightbulb. Where should you place the lightbulb? At the focal point of the mirror At the radius of curvature of the mirror At any point, because all rays bouncing off the mirror will be parallel None of the above; you can't make parallel rays with a concave mirror.
At the focal point of the mirror
Which of the following travel at the same speed as light? Cell phone signals Infrared radiation Ultrasonic waves Radio waves X-rays Radar Microwaves Gamma rays.
Cell phone signals, Infrared radiation, Radio waves, X-rays, Radar, Microwaves, Gamma rays
Which of the following can a transformer accomplish? Changing both current and voltage Changing voltage but not current Changing current but not voltage Changing power.
Changing both current and voltage
Two loops of wire are moving in the vicinity of a very long straight wire carrying a steady current Find the direction of the induced current in loop D. clockwise alternating (ac) counterclockwise zero
Clockwise
Now let us assume that we are able to reorientate the wire in (Figure 1) and therefore the direction of current flow. Which of the following situations would result in a magnetic force on the wire that points due north? Check all that apply. Current in the wire flows straight down; the magnetic field points due west. Current in the wire flows straight up; the magnetic field points due east. Current in the wire flows due east; the magnetic field points straight down. Current in the wire flows due west and slightly up; the magnetic field points due east. Current in the wire flows due west and slightly down; the magnetic field points straight down.
Current in the wire flows straight down; the magnetic field points due west. Current in the wire flows straight up; the magnetic field points due east. Current in the wire flows due east; the magnetic field points straight down. Current in the wire flows due west and slightly up; the magnetic field points due east.
When switch S in the figure is open, the voltmeter V of the battery reads 3.07 V . When the switch is closed, the voltmeter reading drops to 3.00 V , and the ammeter A reads 1.60 A . Assume that the two meters are ideal, so they do not affect the circuit. (Figure 1) Find the emf E. Express your answer in volts to three significant digits. E=V when circuit is open
E=3.07 V
F=ILBsin(θ) Now assume that a strong, uniform magnetic field of size 0.55 TT pointing straight down is applied. What is the size of the magnetic force on the wire due to this applied magnetic field? Ignore the effect of the Earth's magnetic field. Express your answer in newtons to two significant figures. F=0.50A x 0.30m x 0.55T x sin(90)
F=8.3x10^-2
F=ILBsin(θ) Consider a wire of length L = 0.30 m that runs north-south on a horizontal surface. There is a current of I = 0.50 A flowing north in the wire. (The rest of the circuit, which actually delivers this current, is not shown.) The Earth's magnetic field at this location has a magnitude of 0.50 gaussgauss (or, in SI units, 0.5×10−4tesla) and points north and 38 degrees down from the horizontal, toward the ground. What is the size of the magnetic force on the wire due to the Earth's magnetic field? In considering the agreement of units, recall that 1T=1N/(A⋅m).(Figure 1) Express your answer in newtons to two significant figures. Fb=(0.5)A x (0.3)m x (0.5x10^-4)T x sin(38)
FB=4.6x10^-6 N
In empty space, which quantity is always larger for X-ray radiation than for a radio wave? Wavelength Speed Amplitude Frequency
Frequency
In a vacuum, what is the difference between a radio wave and an X-ray? Frequency Wavelength Speed.
Frequency Wavelength
Which of the following will generally create a more stable nucleus? Having the same number of electrons as protons Having a larger total binding energy Having more nucleons Having a larger binding energy per nucleon Having more protons than neutrons.
Having a larger binding energy per nucleon
Radon has a half-life of about 1600 years. The Earth is several billion years old, so why do we still find radon on this planet? Ice-age temperatures preserved some of it Heavier unstable isotopes decay into it It is created in lightning strikes Its half-life has decreased over time It is replenished by cosmic rays Its half-life has increased over time.
Heavier unstable isotopes decay into it
Each plate of a parallel-plate capacator is a square with side length r, and the plates are separated by a distance d. The capacitor is connected to a source of voltage V. A plastic slab of thickness d and dielectric constant K is inserted slowly between the plates over the time period Δt until the slab is squarely between the plates. While the slab is being inserted, a current runs through the battery/capacitor circuit. (Figure 1) Assuming that the dielectric is inserted at a constant rate, find the current I as the slab is inserted. Express your answer in terms of any or all of the given variables V, K, r, d, Δt, and ϵ0, the permittivity of free space.
I =((K−1)r2ϵ0V)/dΔt
Learning Goal: To understand the role of the internal resistance of various devices and the use of the ammeter and the voltmeter. Consider the circuit shown.(Figure 1) All wires are considered ideal; that is, they have zero resistance. We will assume for now that all other elements of the circuit are ideal, too: The value of resistance R is a constant, the internal resistances of the battery (r) and the ammeter (RA) are zero, and the internal resistance of the voltmeter (RV) is infinitely large. Now assume that the battery has a nonzero internal resistance r (but the voltmeter and the ammeter remain ideal). What is the reading of the ammeter now? Express your answer in terms of E, r, and R
I =E/(R+r)
Learning Goal: To understand the role of the internal resistance of various devices and the use of the ammeter and the voltmeter. Consider the circuit shown.(Figure 1) All wires are considered ideal; that is, they have zero resistance. We will assume for now that all other elements of the circuit are ideal, too: The value of resistance R is a constant, the internal resistances of the battery (r) and the ammeter (RA) are zero, and the internal resistance of the voltmeter (RV) is infinitely large. What is the reading I of the ammeter? Express your answer in terms of E and R.
I =E/R
Learning Goal: To study the behavior of a circuit containing a resistor and a charged capacitor when the capacitor begins to discharge. A capacitor with capacitance C is initially charged with charge q. At time t=0, a switch is thrown to close the circuit connecting the capacitor in series with a resistor of resistance R. (Figure 1) What is the current I0 that flows through the resistor immediately after the switch is thrown? Express your answer in terms of any or all of the quantities q, R, and C.
I0 =qRC
Now consider what happens when a switch in the circuit is opened. What happens to bulb C? It gets dimmer It gets brighter There is no change.
It gets brighter
Now consider what happens when a switch in the circuit is opened. What happens to bulb A? It gets dimmer It gets brighter There is no change.
It gets dimmer
Now consider what happens when a switch in the circuit is opened. What happens to the brightness of bulb A? It gets dimmer It gets brighter There is no change
It gets dimmer
You are looking straight down on a magnetic compass that is lying flat on a table. A wire is stretched horizontally under the table, parallel to and a short distance below the compass needle. The wire is then connected to a battery so that a current I flows through the wire. This current causes the north pole of the compass needle to deflect term-98to the left. The questions that follow ask you to compare the effects of different actions on this initial deflection. With the wire back at its initial location, you connect a second identical battery in series with the first one. When you close the switch, how does the new angle of deflection of the north pole of the compass needle compare to its initial deflection? It is larger It is smaller It is unchanged.
It is larger
You are looking straight down on a magnetic compass that is lying flat on a table. A wire is stretched horizontally under the table, parallel to and a short distance below the compass needle. The wire is then connected to a battery so that a current I flows through the wire. This current causes the north pole of the compass needle to deflect to the left. The questions that follow ask you to compare the effects of different actions on this initial deflection. If the wire is lowered farther from the compass, how does the new angle of deflection of the north pole of the compass needle compare to its initial deflection? It is larger It is smaller It is unchanged.
It is smaller
Calculate the ratio of the kinetic energy of an electron to that of a proton if their wavelengths are equal. Assume that the speeds are nonrelativistic. Ke/Kp= lambda=h/(mv) ve/vp=mp/me mp/me=1840 (1/2meve^2)/(1/2mpvp^2) me/mp * ve^2/vp^2= me/mp * mp/me= mp/me=
Ke/Kp=1840
The placement of resistors in a circuit is one factor that can determine the current passing through the resistor. You will be given three circuits, and for each circuit you will be asked to compare the current through the various resistors. In each of the circuits, all resistors are identical. Rank below the three identical resistors (A, B, and C) in (Figure 1) on the basis of the current that flows through them. Rank from largest to smallest. To rank items as equivalent, overlap them.
Largest (A), in the middle (B and C)
The placement of resistors in a circuit is one factor that can determine the current passing through the resistor. You will be given three circuits, and for each circuit you will be asked to compare the current through the various resistors. In each of the circuits, all resistors are identical. Rank below the three identical resistors (A, B, and C) in (Figure 2) on the basis of the current that flows through them. Rank from largest to smallest. To rank items as equivalent, overlap them.
Largest (C), in the middle (A and B)
The placement of resistors in a circuit is one factor that can determine the current passing through the resistor. You will be given three circuits, and for each circuit you will be asked to compare the current through the various resistors. In each of the circuits, all resistors are identical. Rank below the four identical resistors (A, B, C, and D) in (Figure 3) on the basis of the current that flows through them.
Largest (D), middle (A), smallest (B and C)
Five equal-mass particles (A-E) enter a region of uniform magnetic field directed into the page. They follow the trajectories illustrated in (Figure 1). Now assume that particles A, B, C, and E all have the same magnitude of electric charge. Rank the particles A, B, C, and E on the basis of their speed. Rank from largest to smallest. To rank items as equivalent, overlap them.
Largest: A, Middle: B, Smallest: C and E
A long straight wire carries a current I as shown in (Figure 1). A small loop of wire rests in the plane of the figure. Which of the following will not induce a current in the loop? Increasing the current in the straight wire Moving the loop in a direction parallel to the wire Rotating the loop so that it becomes perpendicular to the plane of the figure Moving the loop farther from the wire without rotating it Moving the loop farther from the wire while rotating it.
Moving the loop in a direction parallel to the wire
A single resistor is wired to a battery as shown in (Figure 1) below. Define the total power dissipated by this circuit as P0. Now, a second identical resistor is wired in series with the first resistor as shown in the second diagram to the left (Figure 2). What is the power, in terms of P0, dissipated by this circuit? Express your answer in terms of P0
P0/2
Learning Goal: To understand how to calculate capacitance, voltage, and charge for a combination of capacitors connected in series. Consider the combination of capacitors shown in the figure.(Figure 1) Three capacitors are connected to each other in series, and then to the battery. The values of the capacitances are C, 2C, and 3C, and the applied voltage is ΔV. Initially, all of the capacitors are completely discharged; after the battery is connected, the charge on plate 1 is Q. Find the charge Q on the first capacitor. Express your answer in terms of C and ΔV1.
Q=CΔV1
Which of the following will not increase a generator's voltage output? Rotating the generator faster Increasing the area of the coil Increasing the magnetic field through the coil Rotating the magnetic field so that it is more closely parallel to the generator's rotation axis Increasing the number of turns in the coil.
Rotating the magnetic field so that it is more closely parallel to the generator's rotation axis
When moonlight strikes the surface of a calm lake, what happens to this light? All of it reflects from the water surface back to the air All of it disappears via absorption by water molecules All of it enters the water Some of it reflects back to the air; some enters the water.
Some of it reflects back to the air; some enters the water.
Learning Goal: To study the behavior of a circuit containing a resistor and a charged capacitor when the capacitor begins to discharge. A capacitor with capacitance C is initially charged with charge q. At time t=0, a switch is thrown to close the circuit connecting the capacitor in series with a resistor of resistance R. (Figure 1) What happens to the charge on the capacitor immediately after the switch is thrown? The electrons on the negative plate of the capacitor are held inside the capacitor by the positive charge on the other plate. Only the surface charge is held in the capacitor; the charge inside the metal plates flows through the resistor. The electrons on the negative plate immediately pass through the resistor and neutralize the charge on the positive plate. The electrons on the negative plate eventually pass through the resistor and neutralize the charge on the positive plate.
The electrons on the negative plate eventually pass through the resistor and neutralize the charge on the positive plate.
Which of the following statements is true regarding how blackbody radiation changes as the temperature of the radiating object increases? The maximum intensity decreases, and the peak wavelength increases Both the maximum intensity and the peak wavelength increase Both the maximum intensity and the peak wavelength decrease The maximum intensity increases, and the peak wavelength decreases. (lambda (wavelength) *T (temp)=constant)
The maximum intensity increases, and the peak wavelength decreases.
A beam of red light and a beam of blue light have equal intensities. Which statement is true? There are more photons in the blue beam There are more photons in the red beam Both beams contain the same number of photons The number of photons is not related to intensity.
There are more photons in the red beam
A bar magnet is held above the floor and dropped (Figure 1). In case (a), the magnet falls through a wire loop. In case (b), there is nothing between the magnet and the floor. If there is induced current, wouldnt that cost energy? Where would that energy come from in case (a)? There is less kinetic energy in case (a) than in case (b) Induced current doesn't need energy Energy conservation is violated in case (a) There is more gravitational potential energy in case (a) than in case (b).
There is less kinetic energy in case (a) than in case (b)
Which of the following statements about transformers is false? If the voltage in the secondary is higher, the current is lower If the current in the secondary is higher, the voltage is lower Transformers work using ac current or dc current If no flux is lost, the product of the voltage and the current is the same in the primary and secondary coils.
Transformers work using ac current or dc current
Learning Goal: To understand the role of the internal resistance of various devices and the use of the ammeter and the voltmeter. Consider the circuit shown.(Figure 1) All wires are considered ideal; that is, they have zero resistance. We will assume for now that all other elements of the circuit are ideal, too: The value of resistance R is a constant, the internal resistances of the battery (r) and the ammeter (RA) are zero, and the internal resistance of the voltmeter (RV) is infinitely large. What is the reading V of the voltmeter? Express your answer in terms of the EMF E.
V =E
Learning Goal: To understand the role of the internal resistance of various devices and the use of the ammeter and the voltmeter. Consider the circuit shown.(Figure 1) All wires are considered ideal; that is, they have zero resistance. We will assume for now that all other elements of the circuit are ideal, too: The value of resistance R is a constant, the internal resistances of the battery (r) and the ammeter (RA) are zero, and the internal resistance of the voltmeter (RV) is infinitely large. Now assume that the battery has a nonzero internal resistance r (but the voltmeter and the ammeter remain ideal). What is the reading of the voltmeter now? Express your answer in terms of E, r, and R.
V =ER/R+r
Learning Goal: Frequently, several capacitors are connected together to form a collection of capacitors. We may be interested in determining the overall capacitance of such a collection. The simplest configuration to analyze involves capacitors connected in series or in parallel. More complicated setups can often (though not always!) be treated by combining the rules for these two cases. Consider the example of a parallel combination of capacitors: Three capacitors are connected to each other and to a battery as shown in the figure.(Figure 1) The individual capacitances are C, 2C, and 3C, and the battery's voltage is V. If the potential of plate 1 is V, then, in equilibrium, what are the potentials of plates 3 and 6? Assume that the negative terminal of the battery is at zero potential. V and V 2V and 3V V and 0 V/2 and V/3
V and zero
When a generator is used to produce electric current, the resulting electric energy originates from which source? The resistance of the generator's coil Empty space Whatever rotates the generator's axle Back emf The generator's magnetic field.
Whatever rotates the generator's axle
Starting in 2009, TV stations in the U.S. switched to digital signals. To watch today's digital broadcast TV, could you use a pre-2009 TV antenna meant for analog? Explain. No; analog antennas do not receive digital signals No; you cannot receive digital signals through an antenna and need to switch to cable or satellite Yes; digital signals are broadcast with the same carrier frequencies, so your old antenna will be fine No; digital signals are broadcast at different frequencies, so you need a different antenna.
Yes; digital signals are broadcast with the same carrier frequencies, so your old antenna will be fine
A wire loop moves at constant velocity without rotation through a constant magnetic field. The induced current in the loop will be counterclockwise clockwise zero We need to know the orientation of the loop relative to the magnetic field.
Zero because it is moving at a constant speed
If electrons in a wire vibrate up and down 1000 times per second, they will create an electromagnetic wave having a wavelength of 1000 m a speed of 1000 m/s a frequency of 1000 Hz an amplitude of 1000 m
a frequency of 1000 Hz
The alternating electric current at a wall outlet is most commonly produced by using an electric motor a rotating coil that is immersed in a magnetic field accelerating electrons between oppositely charged capacitor plates a connection to rechargeable batteries alternately heating and cooling a wire.
a rotating coil that is immersed in a magnetic field
A nonconducting plastic hoop is held in a magnetic field that points out of the figure (Figure 1). As the strength of the field increases, an induced emf will be produced but no current an induced emf will be produced that causes a counterclockwise current an induced emf will be produced that causes a clockwise current no induced emf will be produced.
an induced emf will be produced but no current
A square loop moves to the right from an area where B⃗ =0, completely through a region containing a uniform magnetic field directed into the figure (Figure 1), and then out to B=0 after point L. A current is induced in the loop only as it passes line J as it passes line J or line L only as it passes line L only as it passes line K as it passes all three lines.
as it passes line J or line L
If the intensity of an electromagnetic wave doubles, the magnetic field must also double the electric field must also double both the magnetic field and the electric field must increase by a factor of √2 Any of the above.
both the magnetic field and the electric field must increase by a factor of √2
The colors in a rainbow are caused by different amounts of absorption for light of different colors by the water in the raindrops the interaction of the light reflected from different raindrops different amounts of refraction for light of different colors by the water in the raindrops the downward motion of the raindrops.
different amounts of refraction for light of different colors by the water in the raindrops
To shoot a swimming fish with an intense light beam from a laser gun, you should aim slightly above the image directly at the image slightly below the image.
directly at the image
If the Earth-Sun distance were doubled, the intensity of radiation from the Sun that reaches the Earth's surface would quadruple drop to 1/4 double drop to 1/2
drop to 1/4
The direction of the magnetic force is perpendicular to both the direction of the current flow and the direction of the magnetic field. Here is a "right-hand rule" to help you determine the direction of the magnetic force. (Figure 2) Straighten the fingers of your right hand and point them in the direction of the current. Rotate your arm until you can bend your fingers to point in the direction of the magnetic field. Your thumb now points in the direction of the magnetic force acting on the wire. What is the direction of the magnetic force acting on the wire in Part B due to the applied magnetic field? due north due south due east due west straight up straight down
due west
A nucleus has more energy than its component neutrons and protons have when the nucleus is at rest but less energy than when it is moving the same energy as its component neutrons and protons have more energy than its component neutrons and protons have less energy than its component neutrons and protons have.
less energy than its component neutrons and protons have.
The radius of an atom is on the order of 10^−10 m. In comparison, the wavelength of visible light is much smaller about the same size much larger
much larger
Parallel light rays cross interfaces from medium 1 into medium 2 and then into medium 3 as shown in (Figure 1). n1>n3>n2 n2>n1>n3 n3>n2>n1 n2>n3>n1 n1>n2>n3 None of the above.
n2>n1>n3
Two separate but nearby coils are mounted along the same axis. A power supply controls the flow of current in the first coil, and thus the magnetic field it produces. The second coil is connected only to an ammeter. The ammeter will indicate that a current is flowing in the second coil. only when the current in the first coil changes only if the second coil is connected to the power supply by rewiring it to be in series with the first coil only when a steady current flows in the first coil whenever a current flows in the first coil.
only when the current in the first coil changes
Five equal-mass particles (A-E) enter a region of uniform magnetic field directed into the page. They follow the trajectories illustrated in (Figure 1). Which particle (if any) is negatively charged? particle A particle B particle C particle D particle E none
particle A
Five equal-mass particles (A-E) enter a region of uniform magnetic field directed into the page. They follow the trajectories illustrated in (Figure 1). Which particle (if any) is neutral? particle A particle B particle C particle D particle E none
particle D
Who will hear the voice of a singer first: a person in the balcony 53.5 m away from the stage (Figure 1), or a person 1200 km away at home whose ear is next to the radio listening to a live broadcast? person listening to the broadcast person in the balcony
person listening to the broadcast
Five equal-mass particles (A-E) enter a region of uniform magnetic field directed into the page. They follow the trajectories illustrated in (Figure 1). Rank the particles on the basis of their speed. Rank from largest to smallest. To rank items as equivalent, overlap them.
ranking cannot be determined
Light passing through a double-slit arrangement is viewed on a distant screen. The interference pattern observed on the screen would have the widest spaced fringes for the case of red light and a small slit spacing blue light and a large slit spacing red light and a large slit spacing blue light and a small slit spacing d*sin(theta)=m*lambda
red light and a small slit spacing
Learning Goal: To understand why charged particles move in circles perpendicular to a magnetic field and why the frequency is an invariant. A particle of charge q and mass m moves in a region of space where there is a uniform magnetic field B⃗ =B0k^ (i.e., a magnetic field of magnitude B0 in the +z direction). (Figure 1) In this problem, neglect any forces on the particle other than the magnetic force. The fact that the magnetic field generates a force perpendicular to the instantaneous velocity of the particle has implications for the work that the field does on the particle. As a consequence, if only the magnetic field acts on the particle, its kinetic energy will ____________. increase over time decrease over time remain constant oscillate
remain constant
Learning Goal: To understand why charged particles move in circles perpendicular to a magnetic field and why the frequency is an invariant. A particle of charge q and mass m moves in a region of space where there is a uniform magnetic field B⃗ =B0k^ (i.e., a magnetic field of magnitude B0 in the +z direction). (Figure 1) In this problem, neglect any forces on the particle other than the magnetic force. This force will cause the path of the particle to curve. Therefore, at a later time, the direction of the force will ____________. have a component along the direction of motion remain perpendicular to the direction of motion have a component against the direction of motion first have a component along the direction of motion; then against it; then along it; etc.
remain perpendicular to the direction of motion
When you look at a fish in a still stream from the bank, the fish appears shallower than it really is due to refraction. From directly above, it appears Deeper than it really is shallower than its real depth at its actual depth It depends on your height above the water.
shallower than its real depth
Uranium-238 decays to lead-206 through a series of beta decays gamma decays alpha decays some combination of alpha, beta, and gamma decays.
some combination of alpha, beta, and gamma decays.
Elements of the Periodic Table are distinguished by the number of protons, electrons, and neutrons in the nucleus the number of neutrons in the nucleus the number of electrons in the atom the number of protons in the nucleus the number of protons and neutrons in the nucleus.
the number of protons in the nucleus
The half-life of a radioactive nucleus is the time it takes for half of the substance to decay half the time it takes for the entire substance to decay the same as the decay constant half the time it takes for the entire substance to decay and the time it takes for half of the substance to decay (these statements are the same) All of the above.
the time it takes for half of the substance to decay
A laptop computer's charger unit converts 120 VV from a wall power outlet to the lower voltage required by the laptop. Inside the charger's plastic case is a diode or rectifier that changes ac to dc plus a transformer generator transmission line battery.motor.
transformer
When the reflection of an object is seen in a flat mirror, the image is virtual and inverted virtual and upright real and upright real and inverted.
virtual and upright
Suppose you are standing about 3 m in front of a mirror. You can see yourself just from the top of your head to your waist, where the bottom of the mirror cuts off the rest of your image. If you walk one step closer to the mirror you will not be able to see any more of your image you will see less of your image, with the cutoff rising to be above your waist you will be able to see more of your image, below your waist.
you will not be able to see any more of your image
Two loops of wire are moving in the vicinity of a very long straight wire carrying a steady current Find the direction of the induced current in loop C. clockwise alternating (ac) counterclockwise zero
zero, facing the same direction as induced current
A rail gun uses electromagnetic forces to accelerate a projectile to very high velocities. A metal rod of mass 50.0 g and electrical resistance 0.200 Ω rests on parallel horizontal rails that have negligible electric resistance. The rails are a distance L = 10.0 cm apart. (Figure 1)The rails are also connected to a voltage source providing a voltage of V = 5.00 V .The rod is placed in a vertical magnetic field. The rod begins to slide when the field reaches the value B = 9.80×10−2 T . Assume that the rod has a slightly flattened bottom so that it slides instead of rolling. Use 9.80 m/s2 for the magnitude of the acceleration due to gravity. Find μs, the coefficient of static friction between the rod and the rails. Give your answer numerically. force acting on rod: 1LB: 25A(.10m)(9.80x10^-2T)=0.245N Frictional force: μmg----> μ=.245/(0.05x9.8)
μs=0.5
Learning Goal: To understand why charged particles move in circles perpendicular to a magnetic field and why the frequency is an invariant. A particle of charge q and mass m moves in a region of space where there is a uniform magnetic field B⃗ =B0k^ (i.e., a magnetic field of magnitude B0 in the +z direction). (Figure 1) In this problem, neglect any forces on the particle other than the magnetic force. If the resulting trajectory of the charged particle is a circle, what is ω�, the angular frequency of the circular motion? Express ω in terms of q, m, and B0.
ω =qB0/m
Learning Goal: To understand why charged particles move in circles perpendicular to a magnetic field and why the frequency is an invariant. A particle of charge q and mass m moves in a region of space where there is a uniform magnetic field B⃗ =B0k^ (i.e., a magnetic field of magnitude B0 in the +z direction). (Figure 1) In this problem, neglect any forces on the particle other than the magnetic force. At a given moment the particle is moving in the +x direction (and the magnetic field is always in the +z direction). If q is positive, what is the direction of the force on the particle due to the magnetic field? + x direction −x direction + y direction −y direction + z direction − z direction
−y direction
