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Physics 30 > Electromagnetic Radiation (EMR) > Flashcards

Electromagnetic Radiation (EMR) Flashcards

1
Q

what produced electromagnetic radiation

A

accelerating charges

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2
Q

does EMR act like a particle or a wave?

A

both, either

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3
Q

when does EMR act like a wave

A

in diffraction and interference. if the frequency is less than visible light

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4
Q

when does EMR act like a particle

A

when the frequency is greater than visible light

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5
Q

characteristics of red light (left side of visible spectrum)

A

about 700 nm, low energy, low frequency, long wavelength

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6
Q

characteristics of violet light (right side of visible spectrum)

A

about 400 nm, high energy, high frequency, short wavelength

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7
Q

what is ionizing radiation

A

EMR past visible light (ultraviolet, x-rays, and gamma radiation)

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8
Q

what is the universal wave equation

A

c = λf it works for all EMR

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9
Q

what speed does EMR travel at

A

the speed of light, 3.00 x 10^8 m/s

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10
Q

What was the Michelson experiment

A

he used a rotating, 8 sided disk and a mirror 35km (?) away to measure the speed of light. the light bounced off one flat side of the disk, hit the mirror and traveled back to hit a flat side of the disk.

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11
Q

refraction

A

the changing of direction or bending of a ray as it passes from one medium to another. it is caused by a sudden change in speed

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12
Q

when does speed decrease in refraction

A

when θ1 > θ2 . the wave is faster in medium 1

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13
Q

when does speed increase in refraction

A

when θ1 < θ2. the wave is slower in medium 1

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14
Q

what does not change in Snell’s law

A

frequency

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15
Q

dispersion

A

the separation of EMR into individual wavelengths. it occurs when a wave passes from one medium to another. (forms a spectrum)

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16
Q

What happens when EMR travels from a high to low refractive index

A

it bends away from the normal line

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17
Q

critical angle

A

the greatest angle at which a ray of light can strike the boundary between the 2 mediums without causing total internal reflection.

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18
Q

when does total internal reflection occur

A

when the incident angle is greater than the critical angle

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19
Q

what do lenses and mirrors do

A

they redirect the path of EMR and form images

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20
Q

what are the possible characteristics of an image

A

Attitude - inverted or upright
Type - real or virtual
Size - larger or smaller

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21
Q

Diffraction

A

the spreading out of a wave as it passes a corner or through an opening

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22
Q

who thought light was particles

A

Newton

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23
Q

who thought light was waves

A

Huygens

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24
Q

What experiment proved that EMR could behave as a wave

A

Thomas Young’s double slit diffraction experiment

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25
Q

the higher the energy and frequency the

A

shorter the wavelength

26
Q

radio waves

A

used in communication, wavelength = 10^4 - 10^-2 m

27
Q

Microwaves

A

made by oscillation of electrons in vacuum tubes, used in radar, heating, communicating, wavelength = 10^-1 - 10^-4 m.

28
Q

wavelength of red light

A

700 - 750 nm

29
Q

wavelength of blue/violet light

A

400 - 450 nm

30
Q

wavelength of green light

A

550 nm

31
Q

infared radiation

A

made by molecular motion, transitions of valence electrons, used for night vision, identifying heat sources, wavelength = 10^-3 - 10^-7

32
Q

Visible light

A

made by valence electrons dropping from high energy to low energy. wavelength = 400-700nm

33
Q

ultraviolet

A

made by higher energy transitions involving valence electrons, ionizing radiation, wavelength = 4.0x10^-7 - 4.0x10^-9 m

34
Q

x-rays

A

made by sudden deceleration of very high speed electrons, ionizing radiation, wavelength = 10^-9 - 10^-12 m

35
Q

gamma rays

A

made by nuclear reactions, ionizing radiation, penetrates matter very deeply, wavelength = 10^-11 - 10^-16

36
Q

Galileo’s experiment

A

did not work. he tried to measure the speed of light with two lanterns a mile apart but only determined that light was too fast to measure this way.

37
Q

who measured the speed of light by observing eclipses of Jupiter’s moon Io

A

Olaus Romer and Chrisitan Huygens

38
Q

types of mirrors

A

concave converging and convex diverging

39
Q

center of curvature

A

point that represents the center of the sphere from which the mirror was cut

40
Q

Vertex

A

geometric center of curved mirror surface

41
Q

Focal point

A

point where light rays converge or appear to diverge from after being reflected

42
Q

what is something all real images have in common

A

they are all inverted

43
Q

what is something all virtual images have in common

A

they are upright

44
Q

the focal length of converging mirrors is

A

positive

45
Q

the focal length of diverging mirrors is

A

negative

46
Q

the more a medium slows down light,

A

the greater the index of refraction

47
Q

When light passes into a medium with a larger index of refraction

A

it bends towards the normal (FST)

48
Q

When light passes into a medium with a lower index of refraction

A

it bends away from the normal (SFA)

49
Q

what is polarization evidence of

A

that light is a transverse wave

50
Q

what does polarized light do

A

it vibrates in the same plane

51
Q

what color light is more affected by refraction

A

blue/violet

52
Q

what color light is more affected by defraction

A

red

53
Q

in which phenomena does EMR act like a wave

A

diffraction and interference (the double slit experiment), and polarization

54
Q

in which phenomena does EMR act like a particle

A

the Photoelectric Effect and the Compton Effect

55
Q

threshold frequency

A

the minimum frequency needed to release electrons from the metal’s surface

56
Q

work function

A

the minimum amount of energy needed for electrons to leave the surface of a metal

57
Q

Photoelectric formula

A

Ephoton = Ek + W

58
Q

photocurrent vs frequency graph

A

rectangular. there are no electrons before the threshold frequency, then the frequency has no effect

59
Q

photocurrent vs intensity graph

A

linear, for each photon, one electron is released

60
Q

photocurrent vs stopping voltage graph

A

curved down (inverse), electrons originating below surface have greater W and smaller Ek and require a smaller stopping voltage.

61
Q

what is light thought of in the Compton effect

A

a mass-less particle that has momentum

Physics 30 (4 decks)

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