Physics 7120
Name ______________________
Midterm Exam
1. When you blow over the top of a coke bottle, you produce the cavity
resonance frequency of the bottle. If you add water and then blow
over it,
a. The pitch would be higher and the period would be longer
b. The pitch would be higher and the period would be shorter
c. The pitch would be lower and the period would be longer
d. The pitch would be lower and the period would be shorter
2. The spreading out of waves past a small opening is a result of
a. interference
b. reflection
c. diffraction
d. refraction
3. The wave property of light which makes possible the formation of
clear images by the eye is
a. reflection
b. refraction
c. diffraction
d. interference
4. The phenomenon of beats is a result of
a. interference
b. reflection
c. diffraction
d. refraction
5. Light is refracted when it passes from air into the glass of a lens
because
a. it strikes the lens at an angle
b. its speed in the glass is slower than in air.
c. it is partially absorbed by the glass
d. its amplitude changes at the glass interface.
6. Of the following radiation types, which has the highest frequency?
a. gamma rays
b. radio waves
c. ultraviolet
d. blue visible light
7. Explain with the help of a sketch why atoms emit only certain colors
of light. Explain why they absorb the same colors strongly.
8. Sound in air is composed of
a. longitudinal waves
b. transverse waves
c. either transverse or longitudinal waves
d. neither transverse nor longitudinal waves
e. transverse waves on Mon, Wed, and Fri but otherwise longitudinal.
9. Lying on a dock on Lake Lanier after finishing the 7120 course, a
student noted that waves reached the dock every 5 seconds and that the
distance between crests was about 3 meters. Quick as a flash she
calculated the wave speed to be
a. 5/3 m/sec
b. 15 m/sec
c. 3/5 m/sec
d. can't be determined from the data given.
10. When a real image of an object is formed on a screen by a lens, the
image must be
a. inverted
b. larger than the object
c. smaller than the object
d. none of the above is necessarily true.
11. In a rainbow, light is
a. refracted
b. reflected
c. both refracted and reflected
12. A sunset appears red because
a. blue light is scattered out of the sun's rays as they pass through a
longer-than-normal air path.
b. air tends to absorb blue light more than red light.
c. scattering in air progressively lowers the frequency of the
light in its long air path.
d. blue light is refracted out of the beam in the long air path.
13. When a source of sound approaches, measurements will show an
increase in the sound's
a. speed
b. frequency
c. wavelength
d. all of these
e. none of these
14. In AM radio transmission,
a. a high frequency sound is transmitted.
b. sound is transmitted on a radio carrier wave.
c. the sound is amplitude modulated by the electromagnetic carrier wave.
d. an "electric image" of the sound varies the amplitude of a carrier
electromagnetic wave.
15. Which way will the light ray bend from its original path when
entering the glass below?
16. An underlying reason for the warmth of greenhouses is that
a. whitewash on the outer surface of the glass filters ultraviolet
light.
b. glass is transparent to incoming high frequency energy but opaque to
low frequency re-radiated energy.
c. re-radiated energy from plants travels at too low a speed to get
through the glass and is trapped inside.
d. some of the sunlight incident upon plants is converted into energy
by photosynthesis
17. An oar partially immersed in water appears "broken" because of
a. refraction
b. interference
c. diffraction
d. absorption
e. polarization
18. Which of the following is a property of a light wave but not of a
sound wave
a. frequency
b. wavelength
c. polarization
d. interference
e. Doppler effect
19. The characteristic quality of a sustained musical instrument sound
is determined mainly by
a. its pitch
b. its amplitude
c. the relative amplitudes of the upper harmonics of the tone
d. the attack and decay transients and vibrato in the tone
20. Light is emitted when
a. electrons jump from lower to higher levels
b. molecules vibrate
c. electrons jump from higher to lower levels
d. electrons are ejected from atoms
21. Of the following types of electromagnetic radiation, the one with
the shortest wavelength is
a. microwaves
b. radio waves
c. visible light
d. ultraviolet
22. The type of wave most likely to diffract around a building would be
a. an AM radio carrier wave
b. a microwave
c. visible light
d. x-rays
23. Smoke sometimes appears blue because
a. very fine smoke particles selectively scatter short wavelengths to
your eye
b. some types of smoke particles are blue
c. smoke absorbs other colors
d. blue light is more easily transmitted by smoke.
24. Which of the following cannot produce ionization and the radiation
damage effects associated with ionizing radiation
a. x-rays
b. gamma rays
c. microwaves
d. ultraviolet
25. A vibrating string will have certain natural vibration frequencies
or resonances because
a. it is always driven at those frequencies
b. all objects vibrate in harmonics
c. all other frequencies tend to be destroyed by destructive
interference.
d. these frequencies are enhanced by constructive interference
26. If you want to achieve higher resolution with an electron
microscope, you use
a. higher speed electrons because their wavelengths are shorter
b. higher speed electrons because their wavelengths are longer
c. lower speed electrons because their wavelengths are shorter
d. lower speed electrons because their wavelengths are longer
27. When a vibrating metal rod causes the air in a tube to vibrate, the
waves in the air have
a. the same speed as those in the rod
b. the same frequency as those in the rod
c. the same wavelength as those in the rod
c. the same amplitude as those in the rod
28. The velocity of photoelectrons emitted from a surface by the
photoelectric effect is determined by
a. the total energy of the light
b. the intensity of the light
c. the frequency of the light
d. the velocity of the light
29. The wave property that limits the fineness of detail which you can
see with a light microscope is diffraction, which smears out the image.
To get the finest detail you should
a. use longer wavelength light
b. use brighter light
c. use a lens with greater magnification
d. use shorter wavelength light
30. When an electron makes a transition from a high energy state to a
lower energy state
a. it emits a photon of energy equal to the energy of the higher state
b. it absorbs a photon
c. it emits a photon of energy equal to the difference in energy
between the higher and lower states.
d. nonsense - the electron is forbidden to make such a transition.
31. Which colors of light could you mix in equal proportion an get
yellow light as a resulting color. Is this the only way to get that
yellow ? Explain. What color would you mix in equal proportions with
yellow to get white light as a result?
32. Why is the sky blue?
33. A vibrating string of length 120 cm vibrates in a standing wave
mode with three distinct loops in the vibration pattern when driven by
a 120 Hz vibrator. The wave velocity in the string is
a. 1 m/sec
b. 3 m/sec
c. 150 m/sec
d. 96 m/sec
e. none of the above
34. The temperature of a distant incandescent hot object can be
determined by measuring
a. the total radiation received from it.
b. the wavelength at which the emission spectrum peaks
c. the shortest wavelength emitted
d. the shape of the curve of emission as a function of frequency.
35. The resolution of the wave-particle paradox for light is
a. light exhibits its wave properties in some experiments and particle
properties in others - having an essential dual nature.
b. light always behaves as a wave but other rays can show both wave and
particle properties.
c. no one knows what light is
d. light only appears to have particle properties; it is essentially a
wave phenomenon.
36. On some days, air nearest the ground is colder than the air that is
higher up. On one of these days, sound waves
a. tend to be refracted upward
b. tend to be refracted downward
c. travel without refraction through the air.
37. The different spectral colors of light correspond to different
a. frequencies
b. intensities
c. polarities
d. velocities
38. To accommodate for viewing close objects, the eye must change its
a. focal length
b. image distance
c. aperture
d. f-number
whereas to focus closely the camera must change its
a. focal length
b. image distance
c. aperture
d. f-number
39. Which color light has the most energy per photon?
a. red
b. green
c. blue
d. all the same
40. Light intensity from an incandescent source is plotted as a
function of frequency as shown in the radiation curve. If this light is
first passed through a cool gas, the resulting radiation curve would
look like
This best illustrates that the atoms of gas have
a. been excited to higher energy levels
b. absorbed part of the light
c. amplified selective resonant frequencies of the transmitted light.
41. The quantum of light is called a
a. quark
b. lighton
c. lepton
d. photon
and its energy
a. increases with light frequency increases
b. increases with wavelength increases
d. increases with frequency decrease.
d. is independent of wavelength.
42. The lens of a nearsighted person's eye focuses parallel rays of
light
a. on the retina
b. behind the retina
c. in front of the retina
d. does not focus parallel rays at all
because
a. the lens is too strong
b. the lens is too weak
c. of astigmatism
d. the focal length is too short
43. Assuming the settings to be the same, oscilloscope display A
represents a wave of higher
whereas display B represents a wave of higher
a. amplitude
b. frequency
c. velocity
d. wavelength
44. When a 1000 Hz tuning fork is struck and held over the open end of
a cylindrical tube filled with water, the first resonance occurs when
the water level is lowered to 8.5 cm below the top of the tube. This
length corresponds to
a. one quarter wavelength for the sound wave
b. one half wavelength for the sound wave
a. one wavelength for the sound wave
a. nonsense ... it is related to the frequency and not to the
wavelength.
The velocity of sound corresponding to this resonant frequency is
a. 340 m/s
b. 680 m/s
c. 170 m/s
d. 85 m/s
45. The photoelectric effect uses light to
a. eject electrons from metals
b. create electron-positron pairs
c. reflect from metal
d. change into electrons
and demonstrates
a. the wave nature of light
b. the particle nature of light
c. that light can be particle or waves..
d. the reflective property of metals
46. A spectrum of colors seen in gasoline on a wet street is primarily
a result of
a. interference
b. polarization
c. refraction
d. scattering
e. diffraction
where
a. the light reaching the eye is polarized by double reflection
b. only the higher frequencies of light resonate with the gasoline and
H2O molecules.
c. the thin film of gasoline spreads the light out into its component
colors.
d. some colors of light reflecting from the gasoline surface are
canceled by light reflecting from the water surface
47. You are swinging a child on a playground swing and reflect on the
nature of this simple pendulum. You judge that if a second child
climbed onto the swing with the first, the pendulum period will
a. increase
b. decrease
c. stay the same
because
d. the mass has increased, slowing the pendulum
e. the period is independent of the mass
f. pendulum periods increase with mass
48. Pitch of sound corresponds to
a. frequency
b. noise
c. loudness
d. intensity
whereas amplitude of sound waves corresponds to
a. frequency
b. noise
c. loudness
49. Compared to a soft sound, the speed of a loud sound is
a. less
b. greater
c. the same
and compared to a low-frequency sound, higher-frequency sound
travels
a. slower
b. faster
c. the same