Ch 4. light

Question 1

Clicker: What did Einstein win the Nobel Prize for?

a. E=mc2
b. Proving light is a wave
c. Proving light is a particle
d. Theory of relativity

Answer 1

c. proving light is a particle

Question 2

define wavelength
define period
what is frequency?

Answer 2

wavelength= distance between peaksks
period= time between peaks
Frequency=1/ period

Question 3

what is the relationship between wavelength and frequency?

Answer 3

inversely proportional

Question 4

What is the speed o light?

Answer 4

c=2.9979 x 10^8 m/s

Question 5

what does the energy in a wave depend on? (2) How do we increase the energy through these two properties?

Answer 5

Energy depends on frequency and amplitude

Frequency= more oscillations.
Amplitude= higher amplitude.

Question 6

Define wave

Answer 6

a propogation of energy that experiences inference/ diffraction
( when two waves meet, amplify or cancel out)

Question 7

Why do we think of light as a wave?

Answer 7

carries energy

undergoes interference.

Question 8

what is the wavelength range of visable light?

Answer 8

400nm to 700nm

Question 9

When light strikes a materal, what are the four things it can do?

Answer 9

Reflect
transmission
absobtion
scatter

Question 10

Why does the sky look blue?

Answer 10

Bc the atmosphere scatters blue light more than red light.

Question 11

Our atmosphere behaves differently for different colours/ frequencies.
What is it transparent to?
What is it opaque to?

Answer 11

Trans= radio waves, vis light, some UV

Opaque to gamma, xrays, UV light blocked by upper atmosphere. Also infered, and long length radio waves

Question 12

Visible light with wavelengths at the long-wavelength end

(λ=700 nm) appears as which color

Answer 12

red

Question 13

What is thermal light produced by?

Answer 13

charged particles accleration/ changing state.

Question 14

What are the two primary ways in which changes of state occur for light particles?

Answer 14

Collisions and excitations

Question 15

What is black body radiation?

What dies the peak frequency correspond to?

Answer 15

light that is just as easily absorbed as it is emitted.

Peak freq= temperature.

Question 16

Why is black body radiation useful?

Answer 16

Can tell temp of stars, planets, asteroids, nebula.

Question 17

Clicker: A hot object that is glowing orange will become redder as it cools.

a. True
b. False

Answer 17

true

Question 18

isotopes have different

Answer 18

molecular weights due to neutrons

Question 19

Do electron orbitals always exhist when not full?

Answer 19

yes.

Question 20

T/F electrons can absorb partial energies to move between orbitals.

Answer 20

false. must be hit by exact right frequency to be properly excited.

Question 21

where does absorbtion spectra come from?

Emission spectrum?

Answer 21

When light is absorbed by a gas cloud.

when light is reemitted.

Question 22

red shift vs blue shift. moving away vs moving towards.

why?

Answer 22

red shift, moving away.
blue shift, moving towards us.

bc the doppler effect. think of light as a series of waves.

Question 23

What is the size of the doppler shift proportional to?

how can this help us

Answer 23

the radial velocity.

wwe can determine radial speeds with the doppler effect and red and blue shifts.

Question 24

What is the name for the lowest energy form of electromagnetic
radiation?
a. Micro waves
b. Radio waves
c. Infrared waves
d. Gamma waves

Answer 24

radiowaves.

Question 25

An astronomer measures a source of light to have a wavelength of 900 nm. What type of light is this?
Select one:
a. Ultraviolet
b. Microwave
c. Xray
d. Visible
e. Infrared

Answer 25

infrared

Question 26

Why are X-rays and gamma rays considered dangerous types of light?

Answer 26

because they break apart molecules thanks to their very high frequences.

Question 27

At which of these temperatures would a blackbody radiate light mostly in the visible spectrum?
Select one:
a. 6000 K
b. 60000 K
c. None of these; a blackbody does not radiate visible light.
d. 600 K
e. 60 K

Answer 27

6000K