Chapter 5

Question 1

Which part of the electromagnetic spectrum has the highest frequency?
A. gamma
B. visible
C. microwave
D. radio

Answer 1

A. gamma

Question 2

Which term characterizes the height of a wave?
A. amplitude
B. frequency
C. speed
D. wavelength

Answer 2

A. amplitude

Question 3

Which part of the electromagnetic spectrum has the longest wavelength?
A. gamma
B. visible
C. microwave
D. radio

Answer 3

D. radio

Question 4

Which part of the electromagnetic spectrum has the most energy?
A. gamma
B. visible
C. microwave
D. radio

Answer 4

A. gamma

Question 5

What distinguishes one element (such as hydrogen) from a different element (such as carbon)?
A. its temperature
B. the number of electrons it has
C. the number of protons in the nucleus
D. the number of neutrons in the nucleus

Answer 5

C. the number of protons in the nucleus

Question 6

How do we know the Sun is made of mostly hydrogen, instead of mostly carbon?
A. Hydrogen is the element capable of getting the hottest.
B. Hydrogen produces unique absorption lines in the Sun’s spectrum that no other element can.
C. Most of the universe is made of hydrogen, so it just makes sense.
D. We have sent missions to gather some of the solar material and study it in a lab.

Answer 6

B. Hydrogen produces unique absorption lines in the Sun’s spectrum that no other element can.

Question 7

Suppose you have a very hot cloud of gas that is in the process of cooling down. What type of spectrum would you observe?
A. continuous
B. absorption
C. emission
D. X-ray

Answer 7

C. emission

Question 8

What is the doppler effect?

Answer 8

Doppler effect: The motion of a light source toward or away from us changes our perception of the wavelength of the waves reaching us.

Question 9

Suppose you observe four stars to have four different Doppler shifts, indicating
four different radial velocities. Which star is moving the fastest?
A. Star 𝛼, 𝑣r = −10 km/s
B. Star 𝛽, 𝑣r = −50 km/s
C. Star γ, 𝑣r = 20 km/s
D. Star δ, 𝑣r = 40 km/s

Answer 9

B. Star 𝛽, 𝑣r = −50 km/s

Question 10

One emission line of hydrogen occurs at 𝜆 !”#$ = 656.3 𝑛𝑚. Suppose you observe this emission line occurring at different wavelengths in four different stars. Which emission line corresponds with the star that is moving the fastest?
A. 657.3 nm
B. 654.3 nm
C. 659.3 nm
D. 655.3 nm

Answer 10

C. 659.3 nm

Question 11

What is thermal equilibrium?

Answer 11

When a systems energy in (heating) is balanced by its energy emitted (cooling).

Question 12

What happens to atoms at absolute zero?

Answer 12

All motion of the atoms stops.

Question 13

Which star is hottest?
A. a star that radiates mostly blue light
B. a star that radiates mostly yellow light
C. a star that radiates mostly red light
D. a star that radiates mostly infrared light

Answer 13

A. a star that radiates mostly blue light

Question 14

Doubling a star’s temperature will change its flux by how much?
A. It will decrease by half.
B. It will also double.
C. It will quadruple.
D. It will increase 16 times as much.

Answer 14

D. It will increase 16 times as much.

Question 15

Rank the following in order from longest wavelength to shortest
wavelength:
A. gamma rays
B. visible light
C. infrared light
D. ultraviolet light
E. radio waves

Answer 15

E. radio waves
C. infrared light
B. visible light
D. ultraviolet light
A. gamma rays

Question 16

As wavelength increases, the energy of a photon ____________ and its frequency ___________.
A. increases; decrease
B. increases; increases
C. decreases; decreases
D. decreases; increases

Answer 16

C. decreases; decreases

Question 17

Which of the following Doppler shifts indicates the fastest approaching object?
A. 0.04 nm
B. 0.06 nm
C. –0.04 nm
D. –0.06 nm

Answer 17

D. –0.06 nm