LUOA Physics Semester 2
We say that two events occur simultaneously when they
are observed at the same time
How would increasing the frequency of light used in a double slit diffraction experiment change the spacing of the bright bands?
bands will be closer together
An ideal spring-mass oscillator will continue to exhibit simple harmonic motion long after it has been released because of the concept of
conservation of energy
If you were to break a bar magnet in half
each half would have a north pole and a south pole
Which of the following is a vector quantity?
electric field strength
A police car with the siren sounding is approaching a stationary observer. Compared to the sound being produced, the *observer* hears a sound which is
higher in frequency, shorter in wavelength
Two charges are exerting a force on each other. If one of the charges is tripled and the distance between the two charges is cut in half, the force is changed by a factor of ?
if d = 1, r = 0.5 if one charge triples, 1 becomes 3 F = K Q1 Q2/r^2 F = 1*1*3/0.5^2 F = 12 The force is changed by a factor of 12.
In the picture a = 40 degrees and b = 50 degrees. The index of refraction in the incident material is n1=1.5. Find the index of refraction for the refracted material (n2).
(1.5)(sin40) = (n2)(sin50) (1.5)(0.643) = (n2)(0.766) n2 = 1.26
The D string on a violin vibrates at 294 Hz when it is played unfingered (open). What will the frequency of the note be if the string is played when fingered halfway down the neck of the violin?
*need to check (294Hz)(2L) = f2 (2L/2) f2 = 588Hz
What is the potential difference that is established across a 0.5 m long conductive rod when it is being pulled through a 0.25 T magnetic field at a speed of 10 m/s?
1.25V
A 100 ohm resistor has 3 A of current passing through it. If the resistor is replaced by one with a resistance of 200 ohm, how much current passes through the new resistor?
1.5A
What is the frequency of motion for a vertical spring-mass oscillator if a mass of 5 kg stretches the spring by 10 cm?
1.6Hz
As the distance between two charges is doubled, the force exerted by one charge on the other is changed by a factor of
1/4
A 10 watt light bulb is half a meter from a book. How much power in watts does a second light have if it produces the same light intensity at 1 meters.
10W bulb: 10/3.14 = 3.18W/m^2 3.18 = P/(4)(3.14)(1^2) P = 39.94W
A wave is incident with a boundary at an angle of 25 degrees with respect to the normal line. If the wave was traveling at 50 m/s and slows down to 35 m/s in the new material, what is the new direction of travel?
17.2 degrees
Two charges are exerting a force on each other. If one of the charges is doubled, the force is changed by a factor of
2
A light wave traveling through air is incident on a boundary with water at an angle of 20 degrees. Assuming an index of refraction of 1 for air and 1.3 for water, when the ray enters the water *its direction of travel will be*
20 degrees
If the lifetime of a stationary particle is measured to be 4.5x10-5 seconds, the lifetime of the particle when moving at 80% of the speed of light will be
7.5x10^-5 seconds
A pendulum completes 71.1 cycles in 1 minute. What is the frequency of the clock arm pendulum? Report your answer to 2 decimal places.
71.1/60secs = 1.19
What is the size (capacitance) of a capacitor that can store 5x10-3 C of charge when connected to a 6 V source?
8.33x10-4 F
A curved mirror with a magnification of 2.5 creates an image that is 20 cm tall. How tall is the object?
8cm
Which color of light is complementary with magenta?
Green
The two colors that make up cyan light are
Green and Blue
Two waves pass simultaneously through the same medium. If wave A has an amplitude of 20 cm and wave B has an amplitude of 30 cm, what is amplitude of the vibration of the medium at a point where A and B interfere with each other completely constructively. What is the amplitude at a point where the two waves interfere completely destructively?
The amplitudes of the two waves would be 50cm when they interfere constructively. *(A+B)* The amplitudes of the two waves would be -10cm when they interfere destructively. *(A-B)*
A spaceship has a length of 1000.m and a mass of 1.30 x 106 kg before it takes off. After the rocket launch, the ship travels at 2.88 x 108 m/s. What is the apparent mass as seen by a stationary observer?
Mo = 1.30x10^6kg v = 2.88x10^8m/s c = 3x10^8m/s m = 4.6 x10^6 kg
If the power company charges you $0.05 per kWh for electricity, how much does it cost you per month to leave a 60 W light bulb on 24 hours a day?
$2.15
What is the strength of the electric field between the two ends of a conductive rod being pulled through a magnetic field with a strength 5 mT at a speed of 15 m/s?
0.075 V/m
What is the frequency of a wave with a period of 4 seconds?
0.25 Hz
A wave with a wavelength of 0.5 m is incident with a boundary at an angle of 25 degrees with respect to the normal line. If the wave was traveling at 50 m/s and slows down to 35 m/s in the new material, what is the wavelength in the new medium?
0.35 m
What is the resistance of a 7 W light bulb connected to a 3 V circuit? Report the answer to two decimal places.
0.39
The period of motion for a spring-mass oscillator is 1.5 seconds, and the amplitude is 25 cm. What is the maximum speed of the system?
1.05 m/s
In a certain material, a beam of light has a speed of 2.7x108 m/s. What is the index of refraction for the material?
1.11
If the work function for a particular surface is 2.6x10-19 J, what will be the kinetic energy of the electrons emitted when the surface is bombarded with light at a frequency of 5.7x1014 Hz?
1.16x10^-19 J
In the circuit below, R1 = 10 ohm, R2 = 15 ohm, and the battery supplies 6 V. If the current through the battery is 1.5 A, what is the value of R3? (PARALLEL CIRCUIT)
12 ohm
What is the speed of a wave with a wavelength of 0.5 meters and a frequency of 30 Hz?
15 m/s
An electric field causes a 20 C charge to lose 3x104 J of energy. What potential difference does the charge move through?
1500V
What speed does a proton (m = 1.67x10-27) need to travel at in order to double its mass?
2.6x10^8 m/s
What is the energy equivalent of 3 kg of mass?
2.7x10^17 J
A 1 m long wire is moved through a 4x10-3 T magnetic field to produce 6.5 mA of current through a 20 ohm resistor. How fast is the wire moving?
32.5 m/s
What is the resistance of a 10 W light bulb connected to a 3 V circuit? Report the answer to two decimal places.
3volt^2/10watts = 0.9 (WRONG)
How much energy is contained in 5 grams of water?
4.5 x 10^14 J
Wave A has an amplitude of 25 cm and Wave B has an amplitude of 15 cm. If the two waves pass through the same region of space, which of the following is not a possible displacement for a particle of the medium? Please consider both constructive and destructive interference.
50cm
Two tones, 500 Hz and 506 Hz are played simultaneously. The resulting beat *frequency* will be
6 beats/second
What is the magnitude of the force experienced by an electron moving through a magnetic field with a strength of 0.025 T at a speed of 2x106 m/s?
8x10^-15N
How much energy is dissipated (used) through a 12 ohm resistor connected to a 6 V battery in 5 minutes?
900J
Two trains start at stations that are 35 km apart. If Train A heads south at 12 km/hr and Train B heads north at 10 km/hr, how long will it be before they pass each other?
95.5 min
Describe why increasing the total resistance of a circuit will tend to decrease the current. Explain your answer in terms of Ohm's. Provide an example using actual numbers to demonstrate this. Use full sentences.
According to Ohm's Law, I = V/R. Increasing the total resistance of a circuit will tend to decrease the current because the current is inversely proportional to the resistance. For example, if a voltage is at 5V with a resistance of 100 ohms, the current is 0.05mA. However, if the resistance increases to 500, the current decreases to 0.01mA.
In complete sentences describe the differences between adding two colors of light and adding two colors of pigment.
Adding two colors of light produces secondary colors of light. However, adding pigments prevents light from being subtracted and absorbs the colors of light. For example, shining cyan light on a green shirt would result in the shirt appearing to be green. But when magenta light hits a green shirt, the shirt absorbs both the blue and red colors of light that were used to create magenta. The shirt then appears to be black.
Which of the following does not describe an inertial frame of reference?
An object rotating on a turntable
Gravitational forces depend on the property called mass. What comparable property underlies electrical forces?
Charge
A test charge experiences a field strength E when it is located a distance d away from a larger charge. If the test charge is moved to a distance of 2d, the field strength will be
E/4
Calculate the frequency and period of the harmonic motion represented by this graph. You must show all work to receive credit on this problem.
Frequency = 1/time (of one wave) F = 1/2s F = 0.33Hz Period = one wavelength (or T(period) = 1/frequency) P = 2s
In complete sentences describe how we see light and color.
In order to see an object, light hits an object and reflects back to the eye. Reflected light is how we see light and see objects. The eye contains rods and cones which allow us to see colors. The rods allow us to see varying intensities while the cones help us to see color.
In the circuit below, if the value of R3 is increased, how will the equivalent resistance change? (COMBINATION CIRCUIT)
Increase
In the circuit below, the induced motive EMF will ______________ if the speed of the moving conductor is increased.
Increase
Which of the following best explains the results of the Michelson-Morley experiment?
It didn't appear that there was anything like the "ether"
A 20 watt light bulb is 2 meters from the book you are reading. If the *power* doubles what happens to the light intensity on the book at this distance?
It doubles
A 20 watt light bulb is 2 meters from the book you are reading. If the *distance* doubles what happens to the light intensity on the book at this distance?
It is 1/4 times as much
What happens to the energy in a wave when a wave is completely reflected off of a boundary between two materials?
It is sent back through the original medium
Find the maximum kinetic energy emitted from the surface of a substance when the frequency of light emitted is 6.6 x 10^14 and the work needed to remove the photon emitted (ϕ) is 1.65 x 10^-19.
KEmax = (6.6x^10-34)(6.6x10^14)-1.65x10^-19 = 2.7x10^-19J
What geographic direction does the Earth's magnetic field point in the core of the planet?
North to South
In the circuit below, the resistor is replaced with a light bulb. What happens to the light bulb if the moving conductor stops suddenly?
The light goes out immediately
An object appears to be blue when a white light shines on it. Explain in full sentences why it is blue.
The object appears to be blue because the object reflects the color blue when it aborbs all the other colors of light.
Why are light waves not diffracted through an open doorway?
The wavelengths are too small compared to the opening
Explain why there is a net force acting on the pendulum bob or why there is not a net force acting on the pendulum bob when the mass is moving back and forth.
There is a net force acting on the pendulum bob when the mass is moving back and forth. Without a net force being applied to the bob, the bob does not accelerate.
In the circuit below, how will adding another resistor to the circuit change the voltage measured across R1? (PARALLEL CIRCUIT)
V stays the same
In the circuit below, R1 = 15 ohm, R2 = 30 ohm, and R3 = 25 ohm. If the battery provides 12 V, calculate the following: -the equivalent resistance of the circuit -the current through the source -the voltage across R2
the equivalent resistance of the circuit R1 + R2 +R3 = 15+30+25 = 70 ohms the current through the source I = V/R = 12V/70 ohm = 0.17 A the voltage across R2 V2 = I*R2 = 0.17A*30ohm = 5.1V
When an electroscope is charged, the leaves repel each other and remain at an angle. What balances the electric force of repulsion so that the leaves don't separate further?
the force of gravity
If the power company charges you $0.05 per kWh for electricity, how much money would you save each month by switching a 100 W incandescent light bulb with a 12 W compact fluorescent (CFL) bulb? Assume the light is used 6 hours each day.
$0.79
The SI unit of charge is the
Coulomb
A +6x10-6 C charge is placed 4 cm away from a +5x10-6 C charge. What is the force of repulsion that each charge feels?
Fe = k*Q1*Q2/r^2 Fe = (9*10^9)(6*10^-6)(5*10^-6)/(0.04)^2 Fe = 168.75N
Increasing the current flowing through a wire will ______________ the strength of the magnetic field around the wire.
Increase
The resistance of the circuit below will _______________ if the speed of the moving conductor is increased.
Stay the same
An object is placed in a circuit and electrons flow freely through the circuit. This object is a
conductor
The number of coils in a solenoid are doubled. The magnetic field strength _______________.
increases
Which of the following motions represent a positive charge moving from high potential energy to low potential energy?
moving away from a positive charge
A 3x10-7 F capacitor stores 2x10-3 C of charge. - What is the voltage across the plates? - How much energy is stored in the electric field?
* What is the voltage across the plates?* C = Q/V 3*10^-7F = 2*10^-3/V V = 6666.67 *How much energy is stored in the electric field?* PEc = 1/2 CV^2 PEc = 1/2(3*10^-7)(6666.67)^2 PEc = 6.67 mJ
An electron moving at 6x106 m/s to the right is brought to rest by an electric field in a distance of 5 m. You must show your work to earn any credit.
*What is the magnitude of the acceleration that the electron experiences?* a = -(6x106 m/s)^2/2(0.05m) = -3.6*10^14 m/s^2 *What is the magnitude of the force that the field exerts on the electron?* F = m*a F = (9.11*10^-31)(3.6*10^14) F = 3.28*10^-16 N *What is the strength of the electric field?* E = Fe/q E = 3.28*10^-16 N/1.6*10^-19 C E = 2050 N/C
An object with a charge of +5 C is used to charge another object that already has a -3 charge through *conduction.* The final charge on the first object will be
+1 C
An object with a charge of +5 C is used to charge another object that already has a -3 charge through *conduction.* The final charge on the second object will be
+1 C
An object with a charge of +5 C is used to charge a neutral object through *conduction.* The final charge on the second object will be
+2.5 C
An object with a charge of +5 C is used to charge another object that already has a +3 charge through *conduction*. The final charge on the first object will be
+4 C
An object with a charge of +5 C is used to charge another object that already has a +3 charge through *conduction.* The final charge on the *second* object will be
+4 C
An object with a charge of +5 C is used to permanently charge another object through *induction.* The final charge on the second object will be
-5 C
How much charge is stored between the plates of a 0.003 F capacitor when it is connected to a 12 V source?
0.036 C
How much current flows through a 40 W light bulb connected to a 120 V circuit?
0.33 A
A 12 V battery is connected to a 75 ohm resistor. The battery is replaced by a 6 V source and the resistor is replaced with 100 ohm of resistance. The current has changed by a factor of
0.375
In the circuit below, R1 = 15 ohm, R2 = 20 ohm, R3 = 25 ohm, and R4 = 20 ohm. If the battery provides 12 V of potential difference, what is the current through R1? (COMBINATION CIRCUIT)
0.42 A
What is the speed of a wave with a wavelength of 1 meter and a period of 2 seconds?
0.5 m/s
A mass of 5 kg is used to stretch a spring a distance of 10 cm away from its rest length. If the spring has a spring constant of 200 N/m, what is the maximum velocity of the mass *when* it is released?
0.63 m/s
What is the period of motion for a vertical spring-mass oscillator if a mass of 5 kg stretches the spring by 10 cm? (Hint: First solve for k using Newton's Second Law.)
0.63s
What is the wavelength of a 520 Hz sound signal in air?
0.65 m
If a concave mirror has a radius of curvature of 1.5 meters, parallel rays of light will be focused on a spot _______ in front of the mirror.
0.75m
A pendulum is moving with harmonic motion. The amplitude of the pendulum is 5 cm and the maximum velocity is 3 m/s. What is the velocity of the pendulum at the maximum displacement point?
0m/s
Which of the following statements comparing the electrostatic force to the gravitational force is/are true? Both forces involve an inverse square relationship. The gravitational force is a field force, but the electrostatic force is a contact force. The gravitational force can only pull, while the electrostatic force can push or pull.
1 and 3 only
An electron moves through a uniform electric field toward a negatively charged plate. If the electron moves through a potential difference of 75 V in 10 cm, Does the electron gain or lose potential energy? How much work is done on the electron? What is the strength of the electric field?
1. Does the electron gain or lose potential energy? The electron gains potential energy. 2. How much work is done on the electron? W = v*q W = 75V*1.602*10^-19 W = 1.2*10^-17 3. What is the strength of the electric field? 10cm = 0.1m EFS = v/m EFS = 75V/0.1m EFS = 750v/m
What is the resistance of a 2 W light bulb connected to a 7 V circuit? Report the answer to two decimal places.
1.36
How much energy is stored between the plates of a 6.5x10-6 F capacitor when it is attached to a 24 V source?
1.87x10-3 J
A lens with a focal length of 4 cm creates an image at a distance of 8 cm from the lens. How far from the lens is the object located?
1/4cm = 1/u + 1/8cm u = 8cm
What is the focal length of a curved mirror if an object 2.25 meters in front of the mirror creates an image 1.5 meters behind the mirror?
1/f = 1/150cm +1/225cm f = 90cm
When moving from a unknown medium into air, light is internally reflected at any incident angle larger than 24 degrees. What is the index of refraction of the unknown medium?
1/sin24 = 2.46
What is the amplitude of the harmonic motion represented by this graph.
10
In the circuit below, R1 = 9 ohm, R2 = 2 ohm, and R3 = 8 ohm. What is the equivalent resistance of the circuit? (SERIES CIRCUIT)
19
You measure a wave horizontally from crest to trough and find the distance to be 0.5 m. What is the wavelength of the wave?
1m
You measure a wave vertically from crest to trough and find the distance to be 2 m. What is the amplitude of the wave?
1m
A proton moves a distance of 5 cm through an electric field with a strength of 3x103 N/C. What is the strength of the electric field?
2.4x10-17 J
Two electrons are placed 3 cm apart from each other. What is the magnitude of the electrostatic force of repulsion between the two electrons?
2.56x10-25 N
A *200* watt light bulb is half a meter from a book. How much power in watts does a second light have if it produces the same light intensity at *1.5* meters.
200W bulb: 200/3.14 = 63.69W/m^2 63.69 = P/(4)(3.14)(1.5^2)P = 1799.88W
A 20 watt light bulb is half a meter from a book. How much power in watts does a second light have if it produces the same light intensity at *1* meters.
20W bulb: 20/3.14 = 6.37W/m^2 6.37 = P/(4)(3.14)(1^2) P = 80W
A ray of light traveling through the air, with index of refraction of 1, enters a material with an index of refraction of 1.33 at an angle of 30 degrees from the normal line. The angle of refraction will be
22.1 degrees
A sound wave has a wavelength of 1.5 m in air. What is the frequency of the sound wave?
227 Hz
In the circuit below, R1 = 6 ohm, R2 = 9 ohm, and R3 = 9 ohm. What is the equivalent resistance of the circuit?
24
A wave is incident upon a flat surface at an angle of 25 degrees with respect to the normal line. At what angle will the wave be traveling after it is reflected from the surface?
25 degrees
When tuning a piano string to middle C (262 Hz) using a tuning fork, you hear 5 beats per second. What are the two possible frequencies that the piano string is currently tuned to?
262 Hz +5 bps = 267 262 Hz - 5 bps = 257 The two possibilities are 267 and 257. (MIGHT BE WRONG)
Calculate the maximum KE and velocity of an electron ejected from silver by a 275 nm photon. The work needed to remove the photon emitted (ϕ) is 7.5783 x 10-19.
275nm = 2.75x10-7m c = f * wavelength 3 x 10^8 = (2.75x10^-7m)(f) f = 1.09 x 10^15 KEmax = (6.6x10^-34)(1.09x10^15) - 7.58 x 10^-19 KEmax = -3.86x10^-20J KW = 0.5mv^2 -3.86x10^-20J = 0.5(9.11x10^-31kg)v^2 v = 291104.86m/s
In the circuit below, R1 = 15 ohm, R2 = 20 ohm, R3 = 25 ohm, and R4 = 20 ohm. What is the equivalent resistance of the circuit? (COMBINATION CIRCUIT)
28.85 ohm
A copper wire of length L has a resistance of R. What is the resistance of a second copper wire identical to the first, but twice as long?
2R
Which of the following statements describes a field force? 1. They require contact between two objects 2. They can only pull on objects 3. Their strength decreases with distance
3 only
Light travels through space at a speed of 3x108 m/s. The human eye can perceive light waves with wavelengths ranging from about 390 to 700 nm. What is the range of frequencies that can be seen by the human eye? Be sure to show your work.
3*10^8m/s / 3.9*10^-7m = 7.69*10^14 3*10^8m/s / 7*10^-7m = 4.29*10^14 The range that can be seen by the human eye ranges from 4.29*10^14 to 7.69*10^14.
What is the relativistic mass of a proton (m = 1.67x10-27) when it travels at 2.5x108 m/s?
3.02 x 10^-27 kg
How many electrons are needed to make a charge of 3.2 x10-19 C?
3.2 *10-19/ 1.6*10-19 = 2 2 electrons are needed.
In the circuit below, R1 = 10 ohm, R2 = 15 ohm, and R3 = 10 ohm. What is the equivalent resistance of the circuit? (PARALLEL CIRCUIT)
3.75 ohm
On a cold winter day, a spark jumps from your hand to a metal doorknob when your finger is 0.3 cm away from the knob. If there is a potential difference between your hand and the knob of 9000 V, what is the strength of the electric field?
3x10^6 V/m
A car driving along the road at a speed near the speed of light turns on its headlights. From the perspective of an *observer on the side of the road*, the light beams will move away from the car at a speed of
3x10^8 m/s
A car driving along the road at a speed near the speed of light turns on its headlights. From the perspective of the *driver of the car*, the light beams will move away from the car at a speed of
3x10^8 m/s
How many electrons are needed to make a charge of 6.4x10-19 C?
4
Two point charges are 4 cm apart. The are moved to a new separation of 2 cm. By what factor does the resulting mutual force between them change?
4
How much mass would be required to power a 250 W motor for 4 hours? (Hint: Remember that the Work-Energy Theorem states that work equals change in energy. First solve for work to find the energy, which you can then use in the mass-energy equivalence equation.)
4.0 x 10^-11 kg
A string is stretched in such a way that its fundamental frequency of vibration is 210 Hz. Which of the following is another possible frequency of vibration for the string?
420 Hz
A copper wire with a radius of 2 mm has a resistance of R. What is the resistance of a second copper wire of the same length with a radius of 1 mm?
4R
In the circuit below, R1 = 10 ohm, R2 = 15 ohm, and the battery supplies 6 V. If the current through the circuit is 0.2 A, what is the value of R3? (SERIES CIRCUIT)
5 ohm
Two tones, 500 Hz and 506 Hz are played simultaneously. The resulting beats will have a *pitch* of
503 Hz
A police car with the siren sounding is approaching a stationary observer. The siren produces a sound wave with a frequency of 440 Hz. If the car is driving at 50 m/s, what is the frequency of the siren heard by the *observer*?
516 Hz
What is the radius of the path that an electron would follow if it was initially moving at 4x106 m/s in a direction perpendicular to a 3.5 mT magnetic field? (Hint: The magnetic field is providing a centripetal force. So after solving for the force using what is given in the problem, use the equation for centripetal force from earlier in the course to solve for radius.)
6.5mm
A flashlight is turned on inside of a moving train car that is 20 meters long. As observed by a passenger on the train, how long does it take the beam of light to reach the far end of the car?
6.67x10^-8 s
Gamma radiation consists of photons with wavelengths under 3x10-11 m. How much energy would be contained in a single photon of gamma radiation?
6.6x10-15 J
If two successive overtones for a vibrating string are 240 Hz and 300 Hz, what is the fundamental frequency of the string?
60 Hz
A string is stretched in such a way that its fundamental frequency of vibration is 210 Hz. What is the frequency of the third harmonic for this string?
630 Hz
A ray of monochromatic light is incident on the surface of a plane mirror at an angle of 25 degrees from the surface of the mirror. What is the angle of reflection?
65 degrees
A magnifying lens has a magnification ratio of 5:1 . How far away from the lens does an object need to be to create an image 30 cm from the lens?
6cm
A 9.78 V battery is connected to a 4.68 ohm resistor. How much current passes through the resistor? Report your answer to two decimal places.
9.78/4.68 = 2.09
A clock pendulum has an equilibrium (lowest) point of 4.79 cm. The highest point the pendulum reaches in the clock is 98.19 cm. What is the amplitude of the pendulum?
98.19-4.79 = 93.4 (subtract lowest from highest)
In an electrical circuit, increasing the total resistance will ______________ the current.
Decrease
In the circuit below, if the value of R2 is decreased, how will the equivalent resistance change? (COMBINATION CIRCUIT)
Decrease
In the circuit below, how will adding another resistor to the circuit change the current moving through the source? (SERIES CIRCUIT)
Decrease I
In the circuit below, how will adding another resistor to the circuit change the total resistance? (PARALLEL CIRCUIT)
Decrease R
In the circuit below, how will adding another resistor to the circuit change the voltage measured across R1? (SERIES CIRCUIT)
Decrease V
How much energy (in Joules) is contained in a photon of light having a wavelength of 6.62x10-7 m?
E = (6.6x10^-34)(3x10^8)/ 6.62x10^-7 E = 2.99 x 10^-19
Calculate the energy required to move an electron from its ground state (level 1) to an excited state of n=3.
E = 13.6eV(1/1^2 - 1/3^2) = 13.6eV(1-1/9) = *12.08 eV* OR E = 2.18 x 10^-18 Joules(1/1^2 - 1/3^2) = 1.94 x 10^-18 Joules
How much energy is released if the electron drops from level 3 to level 2.
E = 13.6eV(1/3^2 - 1/2^2) = 13.6eV(1/9-1/4) = *-1.89 eV* OR E = 2.18 x 10^-18 Joules(1/3^2 - 1/2^2) = -3.03 x 10^-19 Joules
What is the magnitude of the force exerted on an electron in an electric field with a strength of 6.5 x108 N/C? Remember, the charge on an electron is 1.6 x 10 -19 C
E = Fe/q 6.5*10^8 N/C = Fe/1.6*10^-19C Fe = 1.04*10^-10 The magnitude of the force exerted on an electron in an electric field with a strength of 6.5 x108 N/C is 1.04*10^-10.
A light has a wavelength of 4.88 x 10-7 m. What is the energy of the photons given off?
E = h*c/wavelength E = (6.6x10^-34J*s)(3 x 10^8)/4.88x10^-7E = 4.06x10^-19J
Find the frequency of light that has an energy of 3.12 x 10^-18 J?
E = hf 3.12 x 10^-18 J = (6.6 x 10^-34J*s) (f) f = 4.73 x 10^15
Determine the energy given off by UV light with a frequency of 5.83 x 10^15.
E = hf E = (5.83x10^15)(6.6x10^-34J*s) E = 3.85x10^-18J
What frequency of light is seen when an electron releases 5.7 x 10-17 Joules of energy is released?
E = hf 5.7 x 10^-17 J = 6.6 x 10^-34 * f f = 8.63 x 10^16 Hz
An electron gains 2.5x10-7 J of energy by moving a distance of 3 cm through an electric field. What is the strength of the electric field?
E = k*Q/r^2 E = 8.99*10^9*-1.6*10^-19/0.03^2 E = -1.6*10^-6
A proton gains 3.3x10-10 J of energy by moving a distance of 4 cm through an electric field. What is the strength of the electric field?
E = k*Q/r^2 E = 8.99*10^9*1.6*10^-19/0.04^2 E = 9*10^-7
A test charge of 2 C is placed in a field where the E-field = 7 N/C. What is the force on the test charge? You must show your work to earn any credit.
E*q = F 7*2 = F F = 14 The force on the test charge is 14.
Answer these questions in 3-5 sentences. Use lab observations and ideas to support your answers. a. What is the relationship between the distance and the measured value on the sensor. b.What is the relationship between charge and field strength?
Electric field lines become weaker and more spread out the further it was from the charge. This was seen in the lab observation where the outer lines has less strength and force. The greater a charge, the more force it has, thus increasing field strength. This was seen in the lab observation where areas with dense field lines contained a larger force.
A hard plastic rod is rubbed on a piece of felt and becomes negatively charged. How is that charge acquired?
Electrons move from the felt to the rod
A kilowatt-hour is a unit of
Energy
What is "consumed" in the electrical circuit?
Energy
In your own words, describe why, in a series circuit, the equivalent resistance is equal to the addition of the values of the individual resistors. Explain your answer in terms of conservation of energy and charge. Use full sentences.
Equivalent resistance equals the sum of all resistance in a series circuit. This means that equivalent resistance increase when more resistors are added. Voltage stays the same but is divided among the resistors. Current remains the same through each resistor as there is only one path for the charge to flow through. However the current through the circuit will decrease. It is converted from high energy to low energy so the charge can enter the source once again.
A 3.2 μ C and a -2.0 μ C charge are placed 2.4 cm apart. What is the magnitude of the force of attraction between the charges?
Fe = kQ1Q2/r^2 Fe = (9*10^9)(3.2*10^-6)(-2*10^-6)/(0.024m)^2 Fe = -100 The magnitude of the force of attraction between the charges is 100N.
Describe a situation in your life that can be viewed from two different frames of reference. You cannot use a train in your answer. Your answer should be in complete sentences for full credit.
If I watched a kid throw a ball upwards while he/she was on a moving school bus, the ball would seem to travel in a parabolic motion or seem to move to the side. However, to the kid, the ball just travels up and back down due to gravity. This is an example of two different frames of reference.
A charged particle is brought near an electron and the electron accelerates at a rate of 4.8 x 10-3 m/s2 to the right. You must show all work to earn credit. If the same force acted on a proton, what direction would the proton accelerate? What force is applied to the electron? What is the acceleration of the proton?
If the same force acting on a proton, what direction would the proton accelerate? The proton would accelerate to the left. What force is applied to the electron? F = m*a F = (9.11*10^-3)(4.8*10^-3) F = 4.37*10^-33N What is the acceleration of the proton? F = m*a 4.37*10^-33N = (1.673*10^-27)*a a = 2.6*10^-6
In several sentences, compare and contrast the methods of conduction and induction for charging objects.
In induction charging, charged object A is brought towards object B. However, neither of those objects ever touch. In conduction charging, charged object A would have to come into contact with neutral object B. Their main difference is that induction relies on a changing magnetic field, but conduction requires a power source to charge objects.
In the circuit below, how will adding another resistor to the circuit change the current moving through the source? (PARALLEL CIRCUIT)
Increase I
A 6 V battery is replaced by a 12 V battery in a circuit. The *current* will
Increase by a factor of 2
Please explain how the John Travoltage simulation and the Balloons and Static simulation demonstrate electric charge. Use 3-5 full sentences to explain what you saw in the simulations.
John Travoltage simulation demonstrated how electric charge builds up and is discharged. The closer the arm was to the door, the quicker the static electricity was discharged. When the arm was further away from the door, more charge needed to be built up before it could be released. The Balloons and Static simulation demonstrated how positive and negative charges could be transferred. When the balloon was rubbed against the sweater, negative charges from the sweater transferred onto the balloon. Static cling was created through this and the balloon would move towards the sweater even after being positioned in the middle of the room. The balloon was also able to cling to the wall because of this charge.
Explain in 2-3 complete sentences how light intensity is related to distance.
Light intensity is related to distance because it is measured by how much light energy reaches a certain location. Intensity decreases as distance is increased and vice versa.
A spaceship has a length of 1000.m and a mass of 1.30 x 106 kg before it takes off. After the rocket launch, the ship travels at 2.88 x 108 m/s. What is the apparent length as seen by a stationary observer?
Lo = 1000m v = 2.88x10^8m/s c = 3x10^8m/s L = 280m
What is the resistance of a 5 W light bulb connected to a 2 V circuit? Report the answer to two decimal places.
P = V^2/R 5 = 4/R R = 4/5 = .8 OR 5=2^2/R so R=4/5 (both method works)
The ratio of the energy contained in a quantum of light to its frequency is known as
Planck's constant
What component in the water system plays the same role as the *potential source in the electrical circuit*?
Pump
Copper has a resistivity of 1.68x10-8 ohm*m. If a piece of copper has a length of 1.5 m and a radius of .5 mm, what is the resistance of the wire?
R = p*L/3.14(r)^2 R = (1.68x10-8 ohm*m)*1.5m/3.14*(0.0005m)^2 R = 0.032 ohms
Copper has a resistivity of 1.68x10-8 ohm*m. If a piece of copper has a length of 2.5 m and a radius of .15 mm, what is the resistance of the wire?
R =p*L/3.14(r)^2 R = (1.68x10-8)(2.5m)/3.14*(0.0015m)^2 R = 5.94*10^-3 ohms ANSWER: 0.6 ohm
The two colors that make up magenta light are
Red and Blue
What relationship did you observe between the distance the balls are apart and the force on each ball. Answer in full sentences using data from your data table in your answer.
The force between the balls increased when the distance was increased. When distance remained the same in trial one, there was force required to repel the balls remained the same.
What relationship did you observe between the charges on the balls and the force on each ball. Answer in full sentences using data from your data table in your answer.
The force on each ball was proportionate to the charges on the balls. As charge increases, force increases as well.
A rubber rod with a charge of -2x10-3 C charge is brought near a grounded neutral conductor. The wire to ground is removed while the charged rod is still near the conductor. The rod is then removed. Next the conductor is used to charge a second neutral object using conduction. What is the resulting charge on the conductor? What is the charge on the second neutral object? Briefly explain why in a few sentences.
The neutral conductor then becomes positively charged by 1*10^-3C. This is because the electrons in the negative charge would repel the electrons in the neutral conductor. The charge on the second neutral object would become negatively charged due to the fact that there are more electrons than protons. The second object would be attracted to the conductor.
Describe two relationships you saw between the variables listed below based on your lab simulation graphs.You must use full sentences and describe observations from the simulation to earn full credit. Describe the relationship of 2 of these: Area vs. Capacitance Area vs. Charge Stored Separation vs. Capacitance Separation vs. Charge Stored
The relationship between separation and charge stored was inverse. The amount of charged stored increased as the distance between the plates decreased. However, the relationship between area and capacitance was linear. When the area of the plate was enlarged, the capacitance increased as well.
Using observations from the lab work. You must use full sentences and describe observations from the simulation. a. Explain the relationship of the dielectric constant and capacitance. b. Explain the relationship of the dielectric constant and stored charge.
There is a linear relationship between the dielectric constant and capacitance, as well as between the dielectric constant and stored charge. It was observed from the lab that as I increased the dielectric constant, both capacitance and stored charged increased as well.
An astronaut on a spaceship inadvertently lets go of a tool and notices that it floats in the same location where it was released. What can we tell about the astronauts frame of reference?
There is not enough information given
A capacitor stores 4.2x10-4 J of energy when connected to a 12 V source. How much charge is stored on the plates of the capacitor?
Try using Q = C*V ANSWER: 7x10^-5 C 4.38x10^14 electrons
In the circuit below, how will adding another resistor to the circuit change the voltage measured across the battery? (PARALLEL CIRCUIT)
V stays the same
In the circuit below, how will adding another resistor to the circuit change the voltage measured across the battery? (SERIES CIRCUIT)
V stays the same
A 4.98 V battery is connected to a 3 ohm resistor. How much current passes through the resistor? Report your answer to two decimal places.
V/R = 4.98v/3ohm = 1.66A
A wave slows down when it enters a new material. What other change must happen to the wave?
Wavelength decreases
What component of the electrical circuit plays the same *role as pipes in the water system*?
Wires
The diagram below shows Electric Fields.JPG
a parallel plate capacitor
What type of force holds the nucleus of an atom together
a strong force that can act over a short distance
A mass of 5 kg is used to stretch a spring a distance of 10 cm away from its rest length. If the spring has a spring constant of 200 N/m, at what location does the mass reach maximum velocity *after* it is released?
at the equilibrium position
If an incident wave speeds up upon entering a new material, its direction of travel will ________________.
be further from the normal line
How would placing a material that is a better insulator (than air) affect the a capacitor when it is stays connected to the same voltage source?
capacitance increases; stores more charge
In a double slit experiment, *bright bands represent* areas where _______________ interference is occurring as the waves strike the screen.
constructive
In a double slit experiment, *increasing the distance* between the slits will ______________ the distance between the bright bands.
decrease
In non-Ohmic resistors, such as lightbulbs, resistance is highly dependent on temperature. As the temperature increases, so does the resistance. This will tend to _____________ the current in the circuit.
decrease
Increasing the *spring constant* of a spring-mass oscillator will ______________ the period of motion.
decrease
Increasing the speed of an object will ___________ the length of the object when observed from a frame of reference that is relatively at rest.
decrease
Passing current through a resistor is a way to _______________ the energy of the charges.
decrease
A plastic lens is thicker around the edges than it is near the center. The lens will make the rays of light __________ and create a _____________ focal point
diverge; virtual
The rays of light passing through a _________________ lens will create a virtual image because they spread apart as they pass through the lens.
diverging
At the end of the 19th century, physicists assumed that light waves must be traveling through a medium like mechanical waves do. They called this medium
ether
An opera singer can hit a note and break a wine glass because the note and the vibration in the glass have the same
frequency
An electron moves through a uniform electric field toward a negatively charged plate. If the electron moves through a potential difference of 25 V in 5 cm. Does the electron gain or lose potential energy?
gain
A wave is reflected back on itself by a surface boundary to create a standing wave. The amplitude of the standing wave will be ____________ the original wave.
greater than
When does the mass of a spring-mass oscillator experience the most force?
immediately upon release
In a double slit experiment, *moving the screen further* away from the slits will _______________ the distance between the bright bands.
increase
Increasing the speed of a moving object will _____________ the mass of the object.
increase
Increasing the speed of the moving frame of reference will ___________ the disparity between the time intervals measured in two frames of reference moving relative to each other.
increase
Increasing the *mass* in a spring-mass oscillator will _______________ the period of motion.
increase AMA and increase efficiency
In the circuit below, how will adding another resistor to the circuit change the total resistance? (SERIES CIRCUIT)
increase R
When a wave enters a material with a lower index of refraction, the *wavelength* of the light wave will
increase.
As the electric field strength at a location increases, the force felt by a test charge at this location
increases
A permanent magnet causing another object to become magnetized as well is known as
induction
When a charge is created by an object brought near, but not touching another object ______________ has occurred.
induction
As you move further away from the source of a sound wave, which of the following characteristics decreases?
intensity
In their experiment the researchers, Michelson and Morley, did not find a difference in
interference patterns
An object is considered to be positively charged because it
is missing electrons
X-Ray machines work because different atoms absorb x-ray photons a different rates. Larger atoms tend to absorb the photons more readily than smaller atoms. Since an x-ray scan of a human body shows bone clearly, bone must be composed of _______________ atoms compared to the soft tissue.
larger
An proton moves through a uniform electric field toward a negatively charged plate. If the electron moves through a potential difference of 25 V in 5 cm. Does the electron gain or lose potential energy?
lose
Light cannot escape from black holes because their immense gravitational strength causes everything to be attracted in toward the event horizon. But photons are a massless form of energy, so why are they affected by a gravitational field?
mass-energy equivalence
Double slit diffraction causes an interference pattern to occur with __________________ waves.
mechanical and electromagenetic
To increase its potential energy, an electron should be
moved further from a positive charge
What is the index of refraction of a material if a ray of light that has a wavelength of 500 nm in air has a wavelength of 225 nm in the material?
n = c/v n = 500nm/225nm n = 2.22
In the picture a = 40 degrees and b = 60 degrees. The index of refraction in the incident material is n1=1.5. Find the index of refraction for the refracted material (n2).
n1sina = n2sinb (1.5)(sin40) = (n2)(sin60) (1.5)(0.643) = (n2)(.866) n2 = 1.11
In the picture a = 35 degrees and b = 50 degrees. The index of refraction in the incident material is n1=1.5. Find the index of refraction for the refracted material (n2).
n1sina = n2sinb (1.5)(sin35) = (n2)(sin50) (1.5)(0.574) = (n2)(0.766) n2 = 1.12
Earth's magnetic field is strongest ______________
near the poles
Which phenomenon best supports the *particle* theory of light?
photoelectric effect
According to quantum theory, light energy is carried by a discrete unit known as a
photon
Which phenomenon best supports the *wave* theory of light?
polarization
Isotopes of the same element must have the same number of
protons
A light wave traveling through air is incident on a boundary with water at an angle of 20 degrees. Assuming an index of refraction of 1 for air and 1.3 for water, when the ray enters the water *it will travel*
slower.
In a vacuum, such as space, all light waves have the same
speed
When a wave enters a material with a lower index of refraction, the *frequency* of the light wave will
stay the same
Car A heads east at 10 km/hr and Car B heads west at 30 km/hr. If they started out 50 km apart, how long will it take for them to pass each other?
t = 50km/ 40km/hr t = 1.25hrs
Car A heads east at 60 km/hr and Car B heads west at 30 km/hr. If they started out 50 km apart, how long will it take for them to pass each other?
t = 50km/ 90km/hr t = 0.56 hrs
An 10-year-old volunteers her 42 year old pet chimpanzee for a space mission. When the chimp returns, the 10 year old is 42 years old and the chimp seems to have aged 10 years. What was the ship's velocity on the trip?
t' = 10 years = 3.1536x10^8 seconds earth time = 32 years = 1.00915x10^9 seconds v = 2.85x10^8m/s
A police car with the siren sounding is approaching a stationary observer. Compared to the sound being produced, the *police officer* hears a sound which is
the same frequency and wavelength
In order for two pulses to cause complete destructive interference, the frequencies must be _______________ and the amplitudes must be ________________ in magnitude and _________________ in direction.
the same; equal; opposite
A proton experiences a force pushing it to the right in an electric field. In the same field, an electron would feel a force
to the left
The fact that light waves can be polarized is proof that it is a
transverse wave
An person in space travels at 80% of the speed of light. The person returns to Earth 25 years later according to his family members on Earth. How many years have passed for the space traveler?
v = 0.8(3x10^8) = 2.4x10^8m/s 25 years = 7.88x10^8 seconds 7.88x10^8s = t'/0.6 t' = 4.73x10^8 seconds 4.73x10^8 seconds = 14.99 years
What is the wavelength of a 410 Hz sound signal in air if the temperature is 35 degrees Celsius? Please show all work to earn credit for this question.
v = 331m/s (0.6m/s/C)(35*C) v = 352 m/s v = 入 *f 352m/s = (410 Hz)(wavelength) wavelength = 0.86m
A plane mirror creates a ____________ image because it is created behind the mirror by the apparent intersection of light rays.
virtual
If I hold a yellow filter up to my eye and look at a banana, the banana appears _______.
yellow
