Download Midterm 2 Solutions

Assessment
https://cms.psu.edu/Section/Assessment/Delivery/AssessmentAl...
1.
The energy of a photon depends on
A) Width
B) Direction
C) Velocity
D) Color
Correct answer(s): D
2.
The organization that studies climate change is
A) IPCC
B) IAEA
C) NAACP
D) AFL-CIO
Correct answer(s): A
3.
In the photoelectric lab that you did, changing the intensity of the light led to
A) A change in the stopping potential
B) More photons to hit the target
C) None of the other choices
D) A change in the color of the light
Correct answer(s): B
4.
Which one of the following is considered unethical in the physicist code of conduct?
A) Fabrication of data
B) All the other choices
C) Plagiarism
D) Falsification of Data
Correct answer(s): B
5.
An electron is placed in a constant electric field to the left. In which direction is the force on the electron?
A) Bottom
B) Up
C) The electron feels no force.
D) Right
E) Left
Correct answer(s): D
6.
AC won out over DC in the war of currents in part because of this critical device:
A) The electric generator
B) The battery
C) The Tesla coil
D) The electric motor
E) The transformer
Correct answer(s): E
7.
I hold a light detector in my hand that can detect individual photons. If I want to increase the likelihood of detecting a photon, I want to
A) Move to where the electromagnetic wave is more intense
B) Make faster measurements.
C) Move to where the electric field is zero.
D) none of the other choices
Correct answer(s): A
8.
Solar cells produce electricity from sunlight using which of the following physical effect?
A) Band Effect
B) Doppler effect
C) Photoelectric effect.
D) Meisner effect
Correct answer(s): C
9.
The color of an oil slick indicate that
A) Oil is made of many different chemicals with different colors
B) Light changes its wavelength when passing through oil
C) Light bends when entering a material
D) Light is a wave and it can have interference
Correct answer(s): D
10. A rotating coil of wire inside of a magnetic field could be
A) an electromagnet
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Assessment
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B) an electric generator of AC current
C) a transformer
D) an electric generator of DC current
Correct answer(s): B
11.
What is the difference between the two batteries depicted below using the water-tower analogy?
A) Different current output
B) Different energy stored
C) Different voltage
D) Different charge
Correct answer(s): C
12.
A typical frequency of infrared radiation by your body is 1.2 x1013 Hz. What is the energy per photon of such radiation? I remind you that Planck's constant is h= 6.6 x10-34 J s
A) 1.66 x 10-38 J
B) 3 x 108 J
C) 7.95 x 10-21 J
D) 2.5x10-5 J
Correct answer(s): C
13. A volt is a measure of
A) Density of electrons
B) Force on the electron
C) Energy per electron
D) Number of electrons per second
Correct answer(s): C
14. Which of the following device contains an electrolyte where positive ions are moving?
A) Capacitor
B) Battery
C) Insulator
D) Conductor
Correct answer(s): B
15. When light made of a single wavelength is shone on a piece of metal, no electrons are seen to be ejected. In order to eject electrons one should:
A) Decrease the intensity of the light
B) Increase the wavelength of the light
C) Decrease the wavelength of the light
D) Increase the speed of the light
Correct answer(s): C
16. Faraday discovered that one could generate electricity with a coil of wire and a magnet by:
A) none of the other choices
B) Having the magnet sit inside the coil of wire
C) Moving the coil of wire towards the magnet
D) just having a really strong magnet anywhere close to the coil of wire (but not moving).
Correct answer(s): C
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Assessment
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17. Is it good (right? ethical? necessary?) to exaggerate a technical/scientific issue in order to get the public concerned? What are the dangers of doing that? What are the dangers of not doing that?
Many possible answers. Was looking for an argument that was making sense.
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18. A politician proposes that to reduce our use of fossil fuels, we should replace all natural gas & oil heat systems in homes with electric heat. As an informed citizen who took Phys 10, what
problems do you see with this proposal?
The problem with this proposal is that almost all electricity is generated by burning fossil fuels
like gas, coal or oil. So this politician is making no sense, changing to electric heat will not
reduce our consumption of fossil fuels in any way.
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19. Name one aspect of the photoelectric experiment that can only be explained if light is a particle.
-- the fact that there is a threshold of frequency
-- the fact that the intensity does not affect the speed of individual electrons.
If light was a wave, frequency should not matter and more intense light should lead to higher
energy electrons
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20. Infrared radiation is also called IR. Describe how it is different from visible light. What emits IR?
it differs about wavelength
objects at room temperature radiate primarily in infrared range.
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