Phys 124 (Imp.)

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Which statement describes photons most accurately?

a. Photons have no mass but do have momentum

b. Photons have mass but no momentum

c. Photons have a birthday sometime in September, but because of quantum mechanics, it is impossible to determine when

d. Photons have neither mass nor momentum

e. Photons have both mass and momentum

A

The importance of the Compton effect is to show that

Select one:

a. photons have wave-like properties

b. electrons have wave-like properties

c. atoms have particle-like properties

d. atoms have wave-like properties

e. photons have particle-like properties

E

Quantum tunnelling refers to:

Select one:

a. a particle appearing on the other side of a region where the particle cannot exist, according to the laws on classical mechanics.

b. the passage of photons through the tip of a scanning tunnelling microscope

c. a particle using its wave-like properties to build an intricate underground network of passages

d. protons passing through a thin sheet of gold foil and bouncing off the heavy nuclei.

e. a wave propagating through a piece of glass and experiencing total internal reflection.

A

If the wavelength of light used to make a two slit interference pattern is doubled, how will the interference patten change?

Select one:

a. The spacing of the bright fringes will increase

b. The spacing of the bright fringes will decrease

c. The brightness of the bright fringes will decrease

d. The brightness of the bright fringes will increase.

A

You can determine the work function for a metal by

Select one:

a. shining higher and higher frequency photons on the metal until electrons are emitted

b. Measuring the mass of the metal and the distance through which it is moved

c. heating the metal and looking for the peak emission according to Wien's Law

d. Increasing the intensity of the light on the metal until electrons are absorbed

e. measuring kinetic energy of electrons emitted below the cutoff frequency.

A

Planck's theoretical explanation for blackbody radiation relied upon

Select one:

a. Defining the Wien displacement law on a quantized grid of wavelengths

b. Selecting a value for the speed of light that was a quantized multiple of the frequency

c. Defining a blackbody to be an ideal body that absorbs all radiation

d. Assuming the energy in a blackbody came only at specific values

e. Letting light waves take on every possible value of energy

D

Consider two objects that are originally separated by a distance d and feel a gravitational force between them. How would the distance between them change if the force that is felt is quadrupled (increased by a factor of 4)?

Select one:

a. Decrease distance by a factor of 2

b. Increase distance by a factor of 2

c. Decrease distance by a factor of 4

d. Increase distance by a factor of 4

A

The Earth exerts a gravitational force of magnitude F on the Moon. Imagine the Earth has 100 times more mass than the Moon. What is the magnitude of the gravitational force that the Moon exerts on the Earth?

Choose the closest answer.

Select one:

a. 10F

b. F

c. 3.2F

d. 100F

B

If g = 9.81 m/s2 is the acceleration of gravity at the Earth's surface. astronauts in the International Space Station feel an acceleration due to gravity from the Earth that is most nearly:

Select one:

a. 0.1g

b. 0

c. 0.9g

d. 1.0g

e. 0.25g

C

The Earth and the Sun are 1x108 km apart. The magnitude of their gravitational potential energy is some quantity U. Jupiter and the Sun are 1x109 km apart. Jupiter is 100 times the mass of the Earth. What is the magnitude of the gravitational potential energy between Jupiter and the Sun?

Select one:

a. 1 U

b. 10 U

c. 0.01 U

d. 100 U

B

The motion of a particle in a longitudinal wave can be described as

Select one:

a. left and right, perpendicular to the direction of wave propagation

b. up and down, perpendicular to the direction of wave propagation

c. around in a circular path, but remaining overall in once place

d. back and forth in the direction of wave propagation

D

To double the speed of a wave on a string, you would have to

Select one:

a. double the mass-per-length of the string

b. decrease the mass-per-length by a factor of twot

c. increase the tension in the string by a factor of 4.

d. reduce the tension in the string by a factor of 4.

e. reduce the tension in the string by a factor of 2.

B

Two sound waves with the same frequency, phase, and amplitude arrive at your ear. Describe what you hear.

Select one:

a. You hear the same frequency, but louder

b. You hear two different sounds, unaffected by each other.

c. You hear nothing

d. You hear two different frequencies

A

Which of the following materials would have the highest speed of sound?

Select one:

a. Helium at 0 °C

b. Air at 20° C

c. Steel

d. Water at 0° C

C