Chapter 5-The Nature of Light

Question 1

how are most observations of space collected

Answer 1

through electromagnetic waves “light”

Question 2

what was light for many centuries

Answer 2

a mystery

Question 3

2 things light is similar to

Answer 3

waves and particles

Question 4

young’s double slit experiment

Answer 4

a screen with two slits was put in front of a light source and projected on to a wall to see what the light would be. it was a center point of light with other patches of light fanned out on its sides

Question 5

photo electric effect

Answer 5

• light shining on a piece of metal can cause electrons to be ejected from the surface
• but it only happens if the light has a wavelength shorter than some value

Question 6

as intensity of light increases what happens to the electrons

Answer 6

they increase but their energy does not

Question 7

what is the equation for frequency

Answer 7

frequency equals speed of light (c) over wavelength of light (lambda)

Question 8

frequency (f)

Answer 8

number of cycles per unit time

Question 9

speed (c)

Answer 9

how fast something moves from one place to another

Question 10

wavelength (lambda)

Answer 10

distance from peak to peak (or trough to trough)

Question 11

low frequency =

Answer 11

long wavelength

Question 12

high frequency=

Answer 12

short wavelength

Question 13

energy

Answer 13

ability to do things

Question 14

how do waves and energy connect

Answer 14

waves transport energy from one location to another

Question 15

light

Answer 15

electromagnetic waves/ radiation

Question 16

what is the quantization of light equation

Answer 16

energy = plank’s constant(h) x speed of light(c) over wavelength(lambda)

Question 17

what equation did Einstein use to explain photoelectric effect

Answer 17

quantization of light

Question 18

in the case of light, waves are carried by what

Answer 18

electromagnetic field

Question 19

all light does what

Answer 19

travel in the speed of light in vaccume

Question 20

what are kirthoffs 3 types of spectrum

Answer 20

• continuous
• emission
• absorption

Question 21

continuous line spectrum

Answer 21

• a hot opaque body, such as a perfect blackbody or a hot dense gas produces this
• the complete rainbow of colors without any spectral lines

Question 22

emission line spectrum

Answer 22

• a hot, transparent gas, produces this
• a series of bright line against a dark background
• ex: neon sign

Question 23

absorption line spectrum

Answer 23

• a cool, transparent, gas in front of a source of continuous spectrum produces this
• a series of dark lines among the colors of a continuous spectrum

Question 24

what type of spectra does a star produce

Answer 24

a continuous spectrum

Question 25

blackbody

Answer 25

- EMITS radiation only according to its temperature - a perfect body does not exist - it absorbs all of the radiation that falls of it - does not reflect any light

Question 26

all electromagnetic wavelengths can be what

Answer 26

- emitted from a blackbody - but same intensity at all wavelengths - peak wavelength depends on temperature

Question 27

a blackbody is pretty much what

Answer 27

a star

Question 28

wiens law

Answer 28

0. 0029mK/T - lower temps have a higher wavelength - higher temps mean lower wavelength

Question 29

Stefan-Boltzmann law

Answer 29

-hotter objects emits more radiation at all wavelengths | Flux=(Constant)Temperature^4

Question 30

which types of stars are blue

Answer 30

hotter stars

Question 31

flux

Answer 31

energy per area per time

Question 32

what is the type of element determined by

Answer 32

the number of protons

Question 33

atomic number

Answer 33

number of protons in nucleus

Question 34

atomic mass number

Answer 34

number of protons and neutrons

Question 35

molecules

Answer 35

consist of two or more atoms

Question 36

what type of line spectra is the solar spectrum

Answer 36

- absorption line spectrum | - this tells us that the sun has an atmosphere

Question 37

Bohr model of the atom

Answer 37

electrons can only occupy certain orbits

Question 38

what are spectral line caused by

Answer 38

when electrons transition between orbits

Question 39

what is an orbital

Answer 39

energy levels of an atom

Question 40

each orbital has what

Answer 40

an associated energy

Question 41

electron always wants to be where

Answer 41

in the ground state at n=1

Question 42

to get an electron form n=1 to n=2 you have to do what

Answer 42

add 10.2 Veto add more energy

Question 43

electron can "move up" by

Answer 43

absorbing a photon

Question 44

electron can "move down" by

Answer 44

emitting an electron

Question 45

we can use the Stefan boltzmanns law to determine what

Answer 45

the flux of energy at the suns surface

Question 46

blue-shifting

Answer 46

anytime a form of light moves towards the radio side of the spectrum (bottom)

Question 47

red-shifting

Answer 47

when light shifts up towards the gamma ray side of the spectrum (top)

Question 48

the light we see now has....

Answer 48

left its source sometime in the past

Question 49

the further out in space we look...

Answer 49

the further back into time we see

Question 50

knowing the flux and size of the star we can determine what

Answer 50

luminosity

Question 51

luminosity

Answer 51

blackbody spectrum+ stefan boltzmann+ size of the star

Question 52

if you know the radius and flux you can get the...

Answer 52

luminosity

Question 53

if you know the flux and luminosity you can get the...

Answer 53

radius

Question 54

power

Answer 54

energy per time

Question 55

doppler effect

Answer 55

parent shift in wavelength due to the relative motion of the source and/or the observer

Question 56

Doppler effect example

Answer 56

sirens of an ambulance are higher pitched as it goes towards you and lower pitched as it goes away

Question 57

when the siren goes away its

Answer 57

redshifted

Question 58

when the siren goes away its

Answer 58

blue shifted

Question 59

the further away the object is in space the more (what color shift is it)

Answer 59

- redshift | - this proves that the universe is expanding