Chapter 5

Question 1

Radiative Energy:

Answer 1

Energy that light carries

Question 2

Power:

Answer 2

The rate of energy flow, measured in watts

Question 3

emmission:

Answer 3

a light bulb emits visible light, the energy of the light comes from the electrical potential energy supplied to the light bulb

Question 4

Absorption:

Answer 4

When you place your hand near an incandescent light bulb the hand absorbs some of the light and warms the hand

Question 5

Transmission:

Answer 5

some forms of matter transmit light, or allows light to pass through it

Question 6

Reflection/scattering:

Answer 6

light can bounce off matter leading it to reflect, when light is bouncing all in the same direction, or scatter, when light is bouncing in all different directions

Question 7

Particles:

Answer 7

atoms and molecules that make up physical objects

Question 8

Waves:

Answer 8

carry energy outward, but do not carry the particles themselves

Question 9

What are the three basic properties of waves:

Answer 9

wavelength, frequency, and speed

Question 10

Wavelength:

Answer 10

the distance from one peak to the next

Question 11

Frequency:

Answer 11

The number of peaks passing by any point in a second

Question 12

Speed:

Answer 12

how fast the waves travel, equal to wavelength x frequency

Question 13

Photon

Answer 13

particle of light

Question 14

Molecules

Answer 14

combinations of atoms

Question 15

Compound

Answer 15

molecule with two or more types of atoms

Question 16

Chemical bond

Answer 16

describes interactions between electrons that bind atoms together

Question 17

Pressure

Answer 17

the force per unit pushing on an object’s surface, high pressure can cause gas to dissolve into a liquid, or reverse the stages of matter

Question 18

Continuous Spectrum

Answer 18

the spectrum of an dense object (such as a lightbulb) that spans all visible wavelengths without interruption

Question 19

Emission Line Spectrum

Answer 19

A low-density object (such as a gas) that emits light only at specific wavelengths that depend on its composition and temperature, producing a spectrum with bright emission lines

Question 20

Absorption Line Spectrum

Answer 20

A combination of emission and continuous spectra.

A cloud of gas between us and a light bulb that can absorb light of specific wavelengths, leaving dark absorption lines in the spectrum.

Question 21

What property does the thermal radiation spectrum depend on

Answer 21

temperature

Question 22

We know how fast a distant galaxy is moving away from us on the basis of its…

Answer 22

spectrum

Question 23

According to the laws of thermal radiation, hotter objects emit photons with

Answer 23

a shorter average wavelength

Question 24

Suppose you know the frequency of a photon and the speed of light. What else can you determine about the photon?

Answer 24

its wavelength and energy

Question 25

We can see the Moon because it

Answer 25

reflects visible light

Question 26

You observe a distant galaxy. You find that a spectral line of hydrogen that is shifted from its normal location in the visible part of the spectrum into the infrared part of the spectrum. What can you conclude?

Answer 26

the galaxy is moving away from you

Question 27

Which of the following conditions lead you to see an absorption line spectrum from a cloud of gas in interstellar space?

Answer 27

the cloud is cool and lies between you and a hot star

Question 28

From shortest to longest wavelength, which of the following correctly orders the different categories of electromagnetic radiation?

Answer 28

gamma, x rays, ultraviolet, visible, infrared, micro, radio

Question 29

Suppose you want to know the chemical composition of a distant star. Which piece of information is most useful to you?

Answer 29

the wavelengths of spectral lines in the star’s spectrum

Question 30

Laboratory measurements show hydrogen produces a spectral line at a wavelength of 486.1 nanometers (nm). A particular star's spectrum shows the same hydrogen line at a wavelength of 486.0 nm. What can we conclude?

Answer 30

the star is moving toward us

Question 31

Thermal radiation is defined as

Answer 31

radiation with a spectrum whose shape depends only on the temperature of the emitting object

Question 32

Suppose that Star X and Star Y both have redshifts, but Star X has a larger redshift than Star Y. What can you conclude?

Answer 32

Star x is moving away from us faster than star Y

Question 33

Betelgeuse is the bright red star representing the left shoulder of the constellation Orion. All the following statements about Betelgeuse are true. Which one can you infer from its red color?

Answer 33

the surface is cooler than the surface of the sun

Question 34

Which of the following stars is the hottest?

Answer 34

a blue star

Question 35

Which of the following observational techniques is most appropriate for measuring Doppler shifts?

Answer 35

spectroscopy

Question 36

Suppose that two stars are identical in every way; for example, same distance, same mass, same temperature, same chemical composition, and same speed relative to Earth, except that one star rotates faster than the other. Spectroscopically, how could you tell the stars apart?

Answer 36

the faster rotating star has wider spectral lines than the slower rotating star

Question 37

When an atom's electrons fall down to lower energy levels in a thin cloud of hot gas, what is produced?

Answer 37

an emission line spectrum

Question 38

We know the Sun is primarily made from hydrogen and helium on the basis of its

Answer 38

spectrum