Chapter 5 - Light

Question 1

Absorption lines

Answer 1

Black lines seen on a spectrum that occur when an object absorbs light

Question 2

Amplitude

Answer 2

The height of a wave
(peak to trough)

Question 3

Atomic mass

Answer 3

The number of protons and neutrons in an atom

Question 4

Atomic number

Answer 4

The number of protons in an atom

Question 5

Doppler effect

Answer 5

Occurs when light from a moving object appears differently depending on how the object is moving

Question 6

Emission lines

Answer 6

Colored lines on a spectrum that occur when an object emits light

Question 7

Frequency

Answer 7

The number of waves that pass a particular point every second

Question 8

Ionization energy

Answer 8

The amount of energy required for an electron to escape an atom

Question 9

Intensity

Answer 9

The amount of radiation emitted at a particular wavelength

Question 10

Isotope

Answer 10

Atoms of the same element that have different numbers of neutrons

Question 11

Photon

Answer 11

A particle of light

Question 12

Power

Answer 12

Energy per unit time

Question 13

Redshift

Answer 13

Occurs when the light from an object appears to have its wavelengths shifted towards the red end of the spectrum

Question 14

Blueshift

Answer 14

Occurs when the light from an object appears to have its wavelengths shifted towards the blue end of the spectrum

Question 15

Wavelength

Answer 15

The distance from peak-to-peak or trough-to-trough in a wave

Question 16

What are the ways in which light and matter interact?

Answer 16

1. Light can pass through matter (transmission)
2. Matter can reflect light
3. Matter can scatter light
4. Matter can absorb light
5. Matter can emit light

Question 17

List the electromagnetic spectrum in order of increasing wavelength.

Answer 17

Gamma rays, X rays, ultraviolet, visible light, infrared, microwaves, radio waves

Question 18

List the electromagnetic spectrum in order of increasing frequency.

Answer 18

Radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays

Question 19

List the electromagnetic spectrum in order of increasing energy.

Answer 19

Radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays

Question 20

How is the wavelength and frequency of light related to its speed?

Answer 20

No relation
Light travels at the same speed regardless of wavelength or frequency

Question 21

How is the energy of a photon related to its frequency?

Answer 21

Higher-energy photons have higher frequencies
(directly proportional)

Question 22

What is the approximate wavelength range of visible light?

Answer 22

400 - 700 nm

Question 23

What is the approximate frequency range of visible light?

Answer 23

400 - 750 THz

(400 - 750 trillion Hz)

Question 24

Emission spectrum:
What does it show, what does it look like, and how is it produced?

Answer 24

1. It shows the wavelengths of light emitted by atoms/molecules
2. It is mostly black with a few colored lines
3. It is produced when a cooler object emits light, such as a cloud of cool gas

Question 25

Absorption spectrum: What does it show, what does it look like, and how is it produced?

Answer 25

1. Shows the complete spectrum of light emitted by an object, minus any blocked by other materials 2. Looks like a complete rainbow with black lines throughout 3. Produced when light from a hot object passes through cooler materials

Question 26

Continuous spectrum: What does it show, what does it look like, and how is it produced?

Answer 26

1. Shows the complete spectrum of colors produced by an object 2. Looks like a full, unbroken rainbow 3. Produced by hot, dense objects (blackbodies)

Question 27

Thermal spectrum: What does it show, what does it look like, and how is it produced?

Answer 27

1. Shows the range of wavelengths of light produced by an object and their relative intensities 2. Looks like a graph of a smooth curve 3. Produced by any hot object emitting light

Question 28

How are electron energy level transitions related to the wavelength/frequency/energy of the absorbed or emitted photon?

Answer 28

The greater the energy transition, the greater the energy of the photon. Higher frequency and shorter wavelength. The smaller the energy transition, the smaller the energy of the photon. Lower frequency and longer wavelength.

Question 29

Describe Wien's Law.

Answer 29

The radiation curve for blackbodies will peak at wavelengths that are inversely proportional to the blackbody's temperature.

Question 30

As an object gets hotter, what happens to the wavelength at which it emits most of its radiation?

Answer 30

They will become shorter

Question 31

As an object gets colder, what happens to the wavelength at which it emits most of its radiation?

Answer 31

They will become longer

Question 32

Describe the Stefan-Boltzmann Law.

Answer 32

For a blackbody, the energy radiated by unit surface area per unit time is proportional to its temperature raised to the fourth power.

Question 33

What happens to the energy emitted by a blackbody as the temperature of that body increases?

Answer 33

It increases

Question 34

If we observe the frequency of light from an object to be higher than the rest frequency, is the object moving towards or away from us?

Answer 34

Towards us (the light is being blueshifted)

Question 35

If we observe the frequency of light from an object to be lower than the rest frequency, is the object moving towards or away from us?

Answer 35

Away from us (the light is being redshifted)

Question 36

If an object is moving towards us, how would the wavelength of its light compare to its wavelength at rest?

Answer 36

The wavelength would be shorter (more blue)

Question 37

If an object is moving away from us, how would the wavelength of its light compare to the wavelength at rest?

Answer 37

The wavelength would be longer (more red)