Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

let's get physical! > 5. let's go to beach-each, let's go get a wave [NTF] > Flashcards

5. let's go to beach-each, let's go get a wave [NTF] Flashcards

waves & particles

1
Q

What is a longitudinal wave?

A

a type pf wave in which the particles oscillate parallel to the direction of the wave

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the wavelength of a wave?

A

the distance between two matching points in neighbouring waves, measured in metres (m)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the amplitude of a wave?

A

the maximum displacement a point moves from its centre of oscillation, measure in metres (m)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What does it mean when a wave has a greater amplitude?

A

Greater energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is time period?

A

the time taken for a point on a wave to move through one complete oscillation, measures in seconds (s)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is frequency?

A

the number of oscillations per second, measured in Hertz (Hz)
OR
the number of waves that pass a point in one second, measured in Hertz (Hz)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

describe electronmagnetic waves

A

transverse waves made up of electric and magnetic fields oscillating perpendicular to the direction of energy transfer. All of the waves travel the same speed in a vacuum.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What does a higher frequency mean?

A

more energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the order of the electronmagnetic spectrum?

A

radio, micro, IR, visible, UV, x-ray, Gamma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is the wavelength of a radio wave?

A

10^3 - 10^1 m

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the wavelength of a microwave?

A

10^-2 m

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is the wavelength of a Infra-red wave?

A

10^-5 m

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is the wavelength of a visible light wave?

A

10^-7 m

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is the wavelength of a ultra violet wave?

A

10^-8 m

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is the wavelength of a x-ray wave?

A

10^-10 m

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is the wavelength of a gamma ray?

A

10^-12 m (+)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

diffraction

A

is the spreading out of a wave as it goes past an obstacle or through a gap

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is Huygens principal?

A

a model where each point on a wave front may be regarded as a source of wavelets expanding from that point.
it allowed a visualisation of how light could penetrate into geometric shadow in a way that particles could not

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is a diffraction grating?

A

a plate on which there is a very large number of parallel, identical, close-spaced slits that splits and diffracts light into several beams travelling in different directions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

When does constructive interfence occur?

A

Occurs when waves are in phase or a path difference of nλ, where a trough and trough meet or a peak and a peak meet. the waves have the same frequency and wavelength but double the amplitude.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

When does destructive interference occur?

A

Occurs when waves are in antiphase or a path difference of (n + 1/2)λ, where a trough of one wave meets a peak of another wave the waves must have the phase difference of 180 degrees. the waves cancel each other out.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

degrees to radians conversion

A

radians = (degrees * pi)/180

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

radians to degrees conversion

A

degrees = (radians *180) / pi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

For two waves of light to be coherent the waves must

A

originate from one source

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

how does a additional converging lens effect the eye

A

decreases the image distance as the lens adds more power

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is a virtual image?

A

cannot be projected onto a screen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Why does intensity decrease over distance

A

the area the wave is spread out over is larger so the intensity is lower (interference can also effect the intensity)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What do all waves do?

A

transfers energy from one point to another

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Describe a longitudinal wave

A

the particles oscillate parallel to the propagation of the wave and direction of energy transfer, making compressions and rarefractions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

dispersion

A

when waves separate out due to a wave travelling through a different medium (different wavelengths travel at different speeds)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is the relationship between intensity and distance?

A

inverse square law

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is intensity?

A

the rate of energy transfer per unit area

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is the speed of sound in air

A

340 m/s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

speed of light in a vacuum

A

zero

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What is phase difference?

A

how much one wave is in front or behind another wave

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What is a transverse wave

A

A transverse wave is one where the particles oscillate perpendicular to the direction of the propagation of the wave and direction of energy transfer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

rarefraction

A

particles that are far apart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

compression

A

particles that are close together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

how does a graph show transverse waves

A

displacement distance graph

displacement shows amplitude

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

How does a graph show longitudinal waves

A

displacement time graph

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What type of wave are EM wave

A

transverse waves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What are wavefronts?

A

the leading edge of one complete wave

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What is coherence?

A

Having the same frequency, wavelength, and unchanging phase difference

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What is superposition?

A

The resultant displacement can be found by adding the two displacements together from interfering waves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

When does superposition occur?

A

Occurs for all waves when they meet, even if they’re no coherent.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

What does superposition of coherent waves show?

A

a constant pattern of interference

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What is path difference?

A

the difference in distance traveled by the two waves from their respective sources to a given point on the pattern

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What is the difference between phase difference and path difference

A

phase difference is worked out by path difference. There could be zero phase difference but still have a path difference.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

What is the structure of an EM wave?

A

electric and magnetic fields which oscillate in phase and are perpendicular to each other

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

What are the characteristics of a progressive wave

A
  • transfers energy
  • each point will reach the same amplitude
  • each particle oscillates over the same path but there is a phase lag between each particle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

What are the characteristics of a standing/stationary wave

A
  • stores energy
  • amplitude varies
  • between two nodes all the particles oscillate in phase; on either side of a node there are outp of phase
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

how are stationary waves formed in a string?

A

the wave reflects back from a terminator and interferes with itself

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

resonant frequencies

A

a natural frequency of vibration determined by the physical parameters of the vibrating object.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

harmonics

A

a wave where its frequency is a multiple of the material natural frequency resulting in a standing wave

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

Where are nodes on a standing wave in a string

A

at the end of the string (+in between depending on the harmonic)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

mass per unit length

A

mass of an object divided by it length, the thickness of string effects this

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

how to calculate wave speed of a standing wave on a string

A

V = √(T/μ)

where μ is the mass per unit length

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

how is a standing wave formed inside a closed pipe?

A

blowing an air column down a closed pipe results in it being reflected back up. The two waves superpose to form a stationary longitudinal wave.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

How is stationary waves in a pipe drawn in a diagram?

A

drawn as a displacement distance graph, so it appears as a transverse wave

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

where is a node formed in a closed pipe standing wave

A

at the closed end

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

why is a node formed at the closed end of a pipe

A

the air cannot oscillate freely

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

Where is an antinode formed in a closed pipe

A

at the open end

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

whats different about closed pipe harmonics

A

it can only form odd harmonics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

Where is a anti node formed in an open pipe

A

at both ends (because they’re open)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

wave diagram

A

shows the wave fronts (straight lines perpendicular to direction of travel)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

ray diagram

A

show a single ray and the direction and action of a wave

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

reflection

A

the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

laws of reflections (2)

A
  • when light is reflected, the incident ray, the reflected ray and the normal all lie inside the same plane
  • the angle i between the incident ray and the normal is the same as the angle r between the reflected ray and the normal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

angles in reflection

A

the angle i between the incident ray and the normal is the same as the angle r between the reflected ray and the normal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

refraction

A

the change in direction of wave propagation due to it moving through a different medium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

why does refraction occur

A

waves travel at different speeds in different mediums.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

less dense -> more dense

how does light bend

A

towards the normal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

snells law

A

n = sini/sinr = c/v

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

refractive index letter

A

n

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

absolute refractive index

A

a ratio of the speed of light in a vacuum to the speed of light in a given medium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

1n2 =

calculating the refractive index between two materials

A

n2/n1

where n2 and n1 are the absolute refractive indexes of each material

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

critical angle

A

the largest angle at which refractuib out of a denser medium is possible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

refraction between two mediums equation

A

n1sin θ1= n2 sin θ2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

how do you calculate the critical angle?

A

by making θ2 90 degrees in the equation:
n1sin θ1= n2 sin θ2

n = 1/sinC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

absolute refractive index of air

A

1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
81
Q

absolute refractive index of water (use to check calculations)

A

1.33

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
82
Q

total internal reflection

A

the complete reflection of a wave where the angle of incidence exceeds the critical angle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
83
Q

if i is less than the critical angle then

A

refraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
84
Q

if i = critical angle =>

A

particial TIR (multiple rays)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
85
Q

if i>critical angle =>

A

TIR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
86
Q

how to measure the refractive index of a solid material

A

use a glass block to shine light through and trace the path

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
87
Q

focal length

A

the distance between the optical centre and the principle focus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
88
Q

diverging lens

A

a concave lens

89
Q

converging lens

A

a bulging lens

90
Q

convex lens

A

converging

91
Q

concave lens

A

diverging

92
Q

ray bending in a converging lens

A

going in: bends towards the normal

going out: bends away from the normal

93
Q

if the object is between the focal length and a converging lens then the image is

A
  • magnified
  • upright
  • virtual image
94
Q

if the object is beyond the focal length of a converging lens then the image is

A
  • magnified
  • inverted
  • real image
95
Q

virtual principal focus

A

is you trace back the diverged rays to a single point

96
Q

power of a diverging lens

A

always negative

97
Q

What does diverging lens do to the image

A
  • diminished
  • upright
  • virtual image
98
Q

what does the focal length depend on

A

the curvature of the surface and the material used

99
Q

the more powerful the lens the…

A

shorter the focal length

100
Q

power of a lens equation

A

P = 1/f

101
Q

lens equation

A

1/f = 1/u + 1/v
distances to real objects and images are postive
distances to virtual images are negative
focal length of converging is positive, focal length of diverging is negative

102
Q

magnification equation

A

magnification = image distance/ object distance

103
Q

real image

A

an image that can be projected onto a screen

104
Q

virtual image

A

an image that can’t be projected onto a screen (appears to come from behind the lens)

105
Q

combing lens powers

A

P = P1 + P2 + P3…

for thin lenses

106
Q

ray diagram for converging lens (object beyond focal length)

A
  1. draw a horizontal line from the top of the object to the y axis then down through the focal point on the opposite side
  2. draw a line directly through the centre of the axes from the top of the object
  3. draw a line through the focal point on the same side of the lens, when it hits the y axis go horizontally across. Where all three lines cross is the top of the image.
107
Q

ray diagram for converging lens (object between focal point and lens)

A
  1. draw a horizontal line from the top of the object to the y axis then down through the focal point on the opposite side
  2. draw a line directly through the centre of the axes from the top of the object
  3. from the two sloped lines dot each one back. Where they cross is the top of the object
108
Q

ray diagram for diverging lens

A
  1. draw a horizontal line from the top of the object to the y axis then align the rule with the focal point on the same side of the lens and draw a line up from the point of the y axis
  2. draw a line directly through the centre of the axes from the top of the object
  3. trace back the upward sloped line, where it crosses the downward diagonal is where the top of the image is
109
Q

not polarised

A

wave oscillates in all directions

110
Q

plane polarsied

A

wave oscillates in one plane only

111
Q

plane polarised examples

A

scattered/reflected light, microwave and radiowave sources

112
Q

polarising longitudinal waves

A

can’t be done

113
Q

crosses polarised

A

when filters are perpendicular to each other so no light can get through

114
Q

diffraction

A

the spreading out of a wave as it goes past an obstacle or through a gap

115
Q

When a wave passes through a gap that is a similar size to their wave length…

A

there is a lot of diffraction

116
Q

monochromatic

A

only one wavelength

117
Q

interference pattern

A

a series of maximum and minimum points that can be seen on a screen from interfering coherent waves

118
Q

nλ =

A

= dsinθ

119
Q

d =

A

slit spacing

120
Q

how to calculate d from lines per m

A

n = 1/(lines per m)

121
Q

What did planck work on?

A
  • He looked at black body radiation
  • He theorised that radiation was emitted in discrete packets of energy
  • he found there was a link between energy and frequency
122
Q

What is a Quanta?

A

discrete packets of energy

123
Q

plancks equation

A

E=hf

124
Q

h value

A

6.633e-34

125
Q

What did einstein theorise?

A

That concentrated packets of energy had particle like properties and were called photons

126
Q

photon

A

concentrated discrete packets of energy which have particle like properties

127
Q

What is the EM spectrum from a particle point of view?

A

many photons with different levels of energy

128
Q

How much do photons weigh?

A

weightless

129
Q

how can photons travel at the speed of light?

A

because theyre weightless

130
Q

what letter represents the speed of light?

A

c

131
Q

how is the equation E = hc/ lambda formed?

A

combining E=hf and c=fλ

132
Q

Electron volt

A

One electronvolt is the energy gained by an electron when it is accelerated through a p.d. of 1v (W= QV)

133
Q

how to convert joules to eV

A

divide by 1.6x10^-19

134
Q

how to convert eV to Joules

A

multiply by 1.6x10^-19

135
Q

how to find plancks constant?

A
  • set up a potential divider circuit with a paralell section with different coloured LEDs, an ammeter and a voltmeter
  • measure the voltage and record the wavelength (read from packet)
  • plot a graph of v agaisnt 1/λ
  • the gradient equals Vλ
  • substitute E = eV into E =hc/λ input gradint value and rearrange to get h
136
Q

Who worked out the photoelectric effect?

A

Einstein

137
Q

What is the photoelectric effect?

A

the emission of electrons from the surface of, generally, a metal in response to incident light.

138
Q

What shows the photoelectric effect?

A

when a charge is given to an electroscope they repel each other so the gold leaf will lift and move away from the metal pole.

139
Q

How can the charge of an electroscope be found?

A

the angle the gold leaf lifts too

140
Q

why does the wave model no backup the photoelectric effect?

A

all the frequencies should combine energy to liberate the electrons

141
Q

how many photons can liberate a single electron?

A

1

142
Q

if wavelength increases…

A

frequency decreases therefore electrons have less kinetic energy and eventually none are liberated

143
Q

if wavelength decrease

A

frequency increases therefore electrons have more kinetic energy

144
Q

if intensity increases

A

more electrons are increased but with the same kinetic energy. if it is below the threshold frequency intensity has NO effect

145
Q

electrons are trapped inside __________ and in order to escape it has to _________

A

energy wells

absorb enough energy

146
Q

How does the material effect the energy well?

A

different sizes therefore different amounts of energy are needed to liberate the electrons

147
Q

work function

A

the amount of energy needed for the electrons to escape their energy well

148
Q

which formula works out the work function

A

hf = Φ + E.K. max

149
Q

if the electron is given just enough energy to release from the energy well its kinetic energy equals 0 therefore….

A

threshold frequency can be found by Φ/h

150
Q

it doesn’t matter how many IR photons land on the metal… if

A

all of them are below the freshold frequency no single electron will be liberated

151
Q

photoelectron

A

a liberated electron

152
Q

intensity is proportional to

A

rate of emmision of photoelectrons

153
Q

Broglie said that for

A

any particle that had momentum it also has wavelength λ = h/p

154
Q

relativistic mass

A

as a particle gets closer to the speed of light the mass tends to increase due to relativistic effects

155
Q

The intensity of a wave at a point represents

A

the probability of a wave being there

156
Q

the electrons have _____ different energy levels by its energy is _______

A

infinite

finite

157
Q

how do you work out the energy changes of an atom?

A

calculate the frequency and wavelength needed to give the energy to move up levels and equally how much is emitted when it falls back down levels

158
Q

emission spectra

A

shows the certain wavelengths of photons which are given off by an element after it is excited and the electrons drop back down to there original energy levels ad emit energy

159
Q

absorption spectra

A

where certain frequencies of light are missing because they’re being absorbed by that element

160
Q

Threshold frequency

A

the lowest frequency of light at which electrons are still released from a surface

161
Q

what experiment determines the work function of different materials and the value of h?

A

stopping voltage experiment

162
Q

What does the graph from the stopping voltage experiment show?

A

gradient = h
F0 (x intercept) = threshold frequency
y intercept = work function

163
Q

What does the y intercept from the stopping voltage experiment show?

A

the voltage needed to stop an electron being liberated by light of 0 frequency and so 0 energy (the work function)

164
Q

What axises are plotted from the stopping voltage experiment?

A 
y = stopping voltage 
x = frequency
165
Q

if the p.d. in a stopping voltage experiment is increased what happens?

A

electrons are accelerated faster as they move in the same direction as the current

166
Q

if the pd. in a stopping voltage experiment is decreased what happens?

A

the battery is more effective than the photoelctric effect therefore the electrons are slowed and start to move backwards.

167
Q

what is stopping voltage?

A

the voltage at which the battery becomes more powerful than the photoelectric effect and the electrons are slowed

168
Q

Why are electrons only emitted about a threshold frequency?

A

Photon energy is proportional to frequency therefore photon energy must be greater than the work function to liberate an electron. All the energy must come from a single electron.

169
Q

Line spectra

A

Specific frequencies/wavelengths show the absorbtion/ emmision lines within a narrow line of wavelengths

170
Q

How do line spectra provide evidence for the existence of energy levels in atoms

A

Photons associated with particular energies show electron transitions up and down the discrete energy levels

171
Q

wave model features

A
  • diffraction
  • refraction
  • reflection
  • have a frequency
  • interfere with each other
  • pass through each other
172
Q

photon model features (features of particles)

A
  • have mass
  • reflect
  • experiences forces between each other
  • have volume
  • can have charge
  • have momentum
  • have density
173
Q

The shorter the pulse…

A

the shorter the distance that can be measured

174
Q

why does the photon model work for photoelectric effect

A
  • The energy of one photon is used to liberate one electron meaning the threshold frequency must be high enough
  • The energy is proportional to the frequency and any energy greater than the work function is transferred t the electron as kinetic energy
175
Q

Why does the wave model not work for the photoelectric effect

A
  • frequency would build up to high enough to liberate and electron
  • K.E. would depend on the intensity of the light
176
Q

long wavelength photon means…

A

less energy levels moved up

177
Q

high frequency photon means…

A

the more energy levels it jumps up

178
Q

how is a photon emitted

A

electrons don’t remain in an excited state so they de-excite and drop down to the ground state and emit energy in the form of a photon

179
Q

how can electrons be excited?

A
  • if a photon is absorbed

- if electrons are hit be other electrons

180
Q

energy delivered by photon (hf) =

A

difference between the energy levels

181
Q

ground state

A

the lowest energy level where electrons are usually found

182
Q

Why are only certain frequencies absorbed by atoms?

A

electrons can only exist in discrete energy levels

183
Q

Kinetic energy gained by accelerating electron through a potential difference =

A

eV

184
Q

the amount of diffraction that a wave undergoes depends on the

A

amplitude of the incident wave and the size of the opening

185
Q

experiment to show that electrons behave as a wave

A

direct the electrons through a crystal. if the size of the crystal atom is similar to the wavelength of the electron it diffracts (a wave property)

186
Q

why is diffraction move obvious with sound than light

A

sound has a longer wavelength so it occurs more at our scale

187
Q

intensity of light through two Polaroids is greatest when

A

the Polaroids are parallel

188
Q

hf

A

energy of a photon

189
Q

Ф

A

The energy required from a single photon to release an electron from its energy well (work function)

190
Q

kinetic energy of photoelectrons depends on…

A

the frequency of the incident photon

191
Q

more intense light means….

A

more photoelectrons released (IF FREQUENCY OVER THRESHOLD FREQUENCY)

192
Q

what does the number of maxima correspond to?

A

the highest integer value of d/λ is the number of maxima on one side of the central order (not including the central order)

193
Q

Why are certain frequencies missing from an absorption spectrum?

A
  • electrons get excited by absorbing photons
  • electrons have fixed energy levels. only certain transitions possible, so only certain photon energies absorbed so some frequencies missing
  • the set of frequencies absorbed depends on the element
194
Q

energy of photon absorbed =

A

difference in energy levels

195
Q

range of visible light wavelengths

A

400nm - 700nm

196
Q

how to get the first order maxima closer together?

A

increase the frequency of the laser

197
Q

as speed decreases…

A

wavelength decreases

198
Q

wave property which only applies to transverse waves?

A

polarisation

199
Q

not polarised

A

oscillates in all the planes perpendicular to the direction of travel

200
Q

standing wave

A

a series of nodes and antinodes formed for interfering coherent waves

201
Q

out of phase value in radians

A

pi

202
Q

in phase value

A

0, 2 pi

203
Q

fundamental frequency

A

lowest frequency of a standing wave that can be set

204
Q

frequency of ultrasound

A

20 000 Hz

205
Q

image from a lens where the object is beyond 2x the focal length

A

inverted
diminished
real

206
Q

object on focal point convex lens

A

ray are parallel, no image will be formed

207
Q

long sight

A

the power is too weak so it doesn’t converge on the retina

208
Q

short sight

A

to powerful, the image converges before the retina

209
Q

milikans experiment

A
  • they let the small drops of oil fall between the two plates
  • by adjusting the pd between the plates the forces were balanced on the drop
  • mg = vQ/d to work out Q
  • to find m they needed to measure the radius, they let it move at terminal velocity and used forces to find r
210
Q

milikans experiment conclusion

A

measured the charge of an oil drop to be always a multiple of 1.6e-19 so he deduced the charge of an electron is 1.6e-19 C

211
Q

milikans experiment set up

A

electric field
atomiser to spray oil drops into the electric field
a microscope to view the oil drops

212
Q

how did the find out r in milikans experiment

A
  • let it fall at terminal velocity and then used forces

- 6πνrv = mg = 4/3ρgπr^3

213
Q

frequency from number of oscillations in a given time

A

f = number of oscillations / time

214
Q

line spectra

A

specific narrow band of frequencies or wavelengths that an element has absorbed/emitted

215
Q

What does firing electrons through a screen show about their nature

A
  • Electrons spread out and form an interference pattern

- Electrons must behave as waves (their wavelength is a similar size to the spacing)

216
Q

What does vertically polarised mean?

A

light only oscillates in the vertical plane perpendicular to the direction of travel

217
Q

Why can two oppositely polarised sources not interfere

A

the oscillate perpendicular to each other so the opposite/ same components cannot undergo superposition

218
Q

explain how refraction is caused (2 parts)

A
  • materials are different densities

- light changes direction and appears to come from another point

219
Q

critical angle

A

the angle of incidence for light travelling from a denser medium has angle of refraction of 90

let's get physical! (20 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions