1
PHYS 187 Exam 1 Questions with Correct Answers |
Updated (100% Correct Answers)
If you have a 100-watt light bulb, how much energy does it use each minute?
Answer: 6,000 joules
The frequency of a wave is Answer: The number of peaks passing by any point
each second, measured in cycles per second, measured in hertz (Hz), equal to the
speed of the wave divided by the wavelength of the wave, AKA all of the above
How are wavelength, frequency and energy related for photons of light? Answer:
Longer wavelength means lower frequency and lower energy
Which of the following statements about x rays and radio waves is not true?
Answer: X rays travel through space faster than radio waves
An electron-volt is Answer: an amount of energy much smaller than a joule
If you heat a gas so that collisions are continually bumping electrons to higher
energy levels, when the electrons fall back to lower the energy levels the gas
produces Answer: an emission line spectrum
When an electron in an atom goes from a higher energy state to lower energy
state, the atom Answer: emits a photon of a specific frequency
When white light passes through a cool cloud of mass, we see Answer: an
absorption line spectrum
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, 2
Which of the following statements about thermal radiation is always true?
Answer: A hot object emits more total radiation per unit surface than a cool
object
You observe the same spectral line in two stars that are identical in every way
except that one rotates faster than the other. How does the spectral line differ
between the two? Answer: the line in the faster rotating star is broader
What is the difference between energy and power? Answer: Power is the rate at
which energy is used, so its units are a unit of energy divided by a unit of time
Suppose you know the frequency of a photon and the speed of light. What else
can you determine about the photon? Answer: its wavelength and energy
When considering light as made up of individual "pieces," each characterized by
a particular amount of energy, the pieces are called Answer: photons
From shortest to longest wavelength, which of the following correctly orders the
different categories of electromagnetic radiation? Answer: gamma rays, x rays,
ultraviolet, visible light, infrared, radio
Thermal radiation is defined as Answer: radiation with a spectrum whose shape
depends only on the temperature of the emitting object
According to the laws of thermal radiation, hotter objects emit photons with
Answer: a shorter average wavelength
© 2026 All rights reserved
PHYS 187 Exam 1 Questions with Correct Answers |
Updated (100% Correct Answers)
If you have a 100-watt light bulb, how much energy does it use each minute?
Answer: 6,000 joules
The frequency of a wave is Answer: The number of peaks passing by any point
each second, measured in cycles per second, measured in hertz (Hz), equal to the
speed of the wave divided by the wavelength of the wave, AKA all of the above
How are wavelength, frequency and energy related for photons of light? Answer:
Longer wavelength means lower frequency and lower energy
Which of the following statements about x rays and radio waves is not true?
Answer: X rays travel through space faster than radio waves
An electron-volt is Answer: an amount of energy much smaller than a joule
If you heat a gas so that collisions are continually bumping electrons to higher
energy levels, when the electrons fall back to lower the energy levels the gas
produces Answer: an emission line spectrum
When an electron in an atom goes from a higher energy state to lower energy
state, the atom Answer: emits a photon of a specific frequency
When white light passes through a cool cloud of mass, we see Answer: an
absorption line spectrum
© 2026 All rights reserved
, 2
Which of the following statements about thermal radiation is always true?
Answer: A hot object emits more total radiation per unit surface than a cool
object
You observe the same spectral line in two stars that are identical in every way
except that one rotates faster than the other. How does the spectral line differ
between the two? Answer: the line in the faster rotating star is broader
What is the difference between energy and power? Answer: Power is the rate at
which energy is used, so its units are a unit of energy divided by a unit of time
Suppose you know the frequency of a photon and the speed of light. What else
can you determine about the photon? Answer: its wavelength and energy
When considering light as made up of individual "pieces," each characterized by
a particular amount of energy, the pieces are called Answer: photons
From shortest to longest wavelength, which of the following correctly orders the
different categories of electromagnetic radiation? Answer: gamma rays, x rays,
ultraviolet, visible light, infrared, radio
Thermal radiation is defined as Answer: radiation with a spectrum whose shape
depends only on the temperature of the emitting object
According to the laws of thermal radiation, hotter objects emit photons with
Answer: a shorter average wavelength
© 2026 All rights reserved
