Chapter 4

Question 1

What is light

Answer 1

Light is radiant energy, a stream of particles called photons, does not need a medium to travel through.

Question 2

Does the speed of light reduce through vacuum

Answer 2

No, the speed of light does not reduce in a vacuum. It only slows down when they pass through an object.

Question 3

What is the speed of light

Answer 3

Almost 300k km/s.

Question 4

What can light sometimes also be described as

Answer 4

It can be described as a wave of changing electric and magnetic energy.

Question 5

What does the energy a photon Carries depend on

Answer 5

It depends on the frequency and wavelength

Question 6

What are the colors the human eye is sensitive to called

Answer 6

The visible spectrum

Question 7

What does the visible spectrum rely on

Answer 7

The wavelength of light received by the eye

Question 8

What is the measurement between wavelengths

Answer 8

Nanometers

Question 9

What is the longest and shortest visible wavelength humans can see

Answer 9

Red=700 nanometers and violet=400 nanometers

Question 10

What is frequency

Answer 10

Frequency is the number of wave crests (top points) that pass a given point in 1 second

Question 11

What is period

Answer 11

It is the time change between passage of successive crests

Question 12

What is white light

Answer 12

White light is a mixture of all colors and wavelengths. A prism can separate these

Question 13

What is the electromagnetic spectrum composed of

Answer 13

It is composed of radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, and gamma rays

Question 14

What is infrared radiation

Answer 14

Discovered by William Herschel, it is the heat radiation related to visible light

Question 15

What is ultraviolet light

Answer 15

Discovered by j.Ritter, it is absorbed by the atmosphere and is responsible for sunburns. It is just beyond the violet end of the visible spectrum.

Question 16

What are radio waves

Answer 16

They were predicted by maxwell and produced by hertz, they are used to discover a wide range of astronomical processes and are used for communication, microwave ovens, and search for extraterrestrials

Question 17

What are x-rays

Answer 17

They were discovered by roentgen, used by doctors to scan bones and organs, used by astronomers to detect black holes and tenuous gas in distant galaxies

Question 18

What are gamma rays

Answer 18

A region of rays relatively unexplored, atmosphere absorbs the entire region, sometimes relieve bursts of gamma ray radiation from deep space

Question 19

What are the energy levels of long and short frequencies

Answer 19

Short wavelength = high frequency = high energy
Long wavelength = low frequency = low energy

Question 20

What is the kelvin temperature scale

Answer 20

It is a scale that relates to an objects molecular movement, as it is cooled the molecular motion comes to a halt and it’s energy approaches zero

Question 21

How do hotter bodies radiate at short wavelengths

Answer 21

Hotter bodies radiate more strongly at shorter wavelengths

Question 22

What is a black body

Answer 22

A black body is an object that absorbs all radiation and heat falling on it

Question 23

What happens if a black body is heated

Answer 23

It radiates more efficiently than any other kind of object. They are excellent absorbers and emitters.

Question 24

What is the structure of an atom

Answer 24

Nucleus=composed of densely packed neutrons and positively charged protons
Cloud of negative electrons= held in orbit around nucleus by positive charge of protons

Question 25

What is an element

Answer 25

It is a substance composed of only atoms that have the same number of protons in their nucleus

Question 26

What are the chemical properties of an element determined by

Answer 26

Their number of electrons

Question 27

When does an atoms energy increase

Answer 27

When an electron moves to an outer orbit, it is said to be excited

Question 28

When does an atoms energy decrease

Answer 28

When an electron moves to the inner orbit

Question 29

What is conservation of energy

Answer 29

It is the fact that energy change in an atom must be compensated elsewhere

Question 30

What are two ways to preserve energy conservation

Answer 30

Absorption and emission of EM radiation

Question 31

What is spectroscopy

Answer 31

It is capturing and analyzing a spectrum

Question 32

What is the role of spectroscopy

Answer 32

Allows the determination of the composition and conditions of an astronomical body, it assumes every atom has a unique spectral signature

Question 33

What are the 3 types of spectra

Answer 33

Continuous,emission-line, and dark-line/absorption-line

Question 34

What is continuous spectrum

Answer 34

It is the spectra of a black body, they are typically solids and dense gasses

Question 35

What is emission-line spectrum

Answer 35

It is produced by hot,tenuous gas. Some examples are fluorescent tubes, aurora, and interstellar clouds

Question 36

What is dark-line / absorption-line spectrum

Answer 36

Light from black body that passes through cooler gas, lines of the sun is an example

Question 37

What wavelengths penetrate the atmosphere

Answer 37

Radio waves, visible light, some infrared.

Question 38

Why do some wavelengths penetrate the atmosphere

Answer 38

It happens through atmospheric windows, which are wavelength regions with high transparency

Question 39

What is the Doppler shift in sound

Answer 39

If a sound has short wavelengths it is higher pitched, if it has long wavelengths it is lower pitched. If the source of the sound is moving the pitch changes

Question 40

What is Doppler’s shift in light

Answer 40

If a source of light is in motion relative to the observer, it’s spectral lines shift to new wavelengths. Shorter wavelengths is called blueshift and longer wavelengths is called redshift

Question 41

What is Doppler shift used for

Answer 41

It is used to determine an object’s velocity