1
Q
Define Amplitude.
A
A Wave’s Maximum Displacement from the Equilibrium Position.
2
Q
Define Frequency.
A
The Number of Complete Oscillations passing through a Point per Second.
3
Q
Define Period.
A
The Time taken for 1 complete Oscillation.
4
Q
Define Wave Speed.
A
The Distance travelled by the Wave per unit Time.
5
Q
Define Wavelength.
A
The Length of 1 complete Oscillation.
6
Q
State the Wave Speed Equation.
A
v = f x Wavelength
7
Q
Define Longitudinal Wave.
A
The Oscillation of Particles is Parallel to the Direction of Energy Transfer.
8
Q
State 3 Examples of Longitudinal Waves.
A
-Sound Waves
-Ultrasound Waves.
-Seismic P Waves
9
Q
State 2 Components of a Longitudinal Wave.
A
Compressions and Rarefactions.
10
Q
State the Pressure of a Rarefaction.
A
Decreased.
11
Q
State the Pressure of a Compression.
A
Increased.
12
Q
State the Displacement of Particles in a Rarefaction.
A
Neighbouring Particles move away from each other.
13
Q
State the Displacement of Particles in a Compression.
A
Neighbouring Particles move towards each other.
14
Q
Define Transverse Wave.
A
The Oscillations of Particles are Perpendicular to the Direction of Energy Transfer.
15
Q
State an Example of Transverse Waves.
A
Electromagnetic Spectrum Waves.
16
Q
State the Speed at which EM Waves travel through a Vaccum.
A
3x10^8ms-1
17
Q
State the 2 types of Graphs used to represent Waves.
A
-Displacement-Distance
-Displacement-Time
18
Q
State what Displacement-Distance Graphs can be used to Measure.
A
Wavelength.
19
Q
State what Displacement-Time Graphs can be used to Measure.
A
Period of a Wave.
20
Q
Define Phase.
A
The Position of a certain point on a Wave.
21
Q
State what Phase/Phase Difference can be Measured in. (3)
A
-Radians
-Degrees
-Fractions
…of a Cycle.
22
Q
Define Phase Difference.
A
How far 2 Oscillations are in their Cycle.
23
Q
Define Path Difference.
A
The Difference in the Distance travelled by 2 Waves.
24
Q
Define Superposition.
A
Where the Displacements of 2 Waves are combined as they pass each other, the Resultant Displacement is a Vector sum of each Wave’s Displacement.
25
Define Coherence.
A Coherent Light Source has the same Frequency, Wavelength and Fixed Phase Difference.
26
Define Wavefront.
A Surface which is used to represent the points of a Wave which have the same Phase.
27
Define Constructive Interference.
Occurs when 2 Waves are in Phase and so their Displacements are Added.
28
Define Destructive Interference.
Occurs when 2 Waves are out of Phase and so their Displacements are Subtracted.
29
Both types of Interference Occur in ...
Superposition.
30
When Molecules in a Polaroid Filter are aligned Horizontally, which Direction is the Polarisation Axis?
Vertical.
31
What happens as a result of 2 Waves in Phase. (3)
-Same Wavelength and Frequency.
-Phase Difference is a Multiple of 360.
-Different Amplitude.
32
What happens as a result of 2 Waves being out of Phase. (2)
-Same Wavelength and Frequency.
-Phase Difference is an Odd Multiple of 180.
33
Define Stationary Wave.
A Wave formed by the Superposition of 2 Progressive Waves travelling in Opposite directions with the same Frequency, Wavelength and Amplitude.
34
State whether Energy is transferred by a Stationary Wave.
It isn't.
35
State what happens when Stationary Waves meet In-Phase. (2)
-Constructive Displacement occurs.
-Antinodes form which are regions of Maximum Displacement.
36
State what happens when Stationary Waves meet Out of Phase.
-Destructive Interference occurs.
-Nodes form which are regions of no Displacement.
37
State the Equation for the Speed of a Transverse Wave on a String.
Sqaured Root of Tension divided by Mass per unit Length of the String.
38
Define Diffraction.
The Spreading out of Waves when they pass through or around a gap.
39
Define Huygen's Principle.
States that every point on a Wavefront is a Point Source to Secondary Wavelets.
40
State what is needed for Diffraction to be Noticeable.
Wavelength needs to be Similar to the Gap Width.
41
Define Diffraction Grating.
A Slide containing many equally spaced Slits that are close together.
42
State what occurs when light passes through a Diffraction Grating.
An Interference Pattern forms composed of Light and Drak Fringes.
43
Define Zero Order Line.
The Ray of Light passing throught the centre of a Diffraction Grating.
44
State where the First Order Lines are Situated.
Either Side of the Zero Order Lines.
45
State the Diffraction Grating Equation.
dsin0 = nλ
46
State what the d stands for in the Diffraction Grating Equation.
Distance between the Slits.
47
State what the n stands for in the Diffraction Grating Equation.
Order
48
Define a Polarised Wave.
A Wave whose Oscillations have been restricted to the same Plane.
49
State which type of Waves can be Polarised.
Transverse Waves.
50
State an Application of Polaroids.
Polarised Sunglasses.
51
Explain how Polarised Sunglasses Work.
They Reduce Glare by Blocking Partially Polarised Light Reflected from Water as they only allow Vertical Oscillations in the Plane of the Horizonatal Filter to Pass through.
52
State the Effect of Polarisation off of a Non-Metalic Surface.
Partial Horizontally Polarised.
53
When Molecules in a Polaroid Filter are aligned Vertically, which Direction is the Polarisation Axis?
Horizontal.
54
State how Aerials work with Polarisation.
Radio/TV Aerials must be aligned with the Transmitter's Polarisation to recieve Maximum Signals.
55
State whether Unpolarised Waves can be Polarised on Reflection from a Surface.
Yes they can.
56
State the Direction of Vibrations in an Unpolarised Wave.
Vibrations in many different Directions.
57
2 Polarising Filters are placed between a Source and a Detector, Perpendicular to each other.
State the Rotations of both 1+2 for Maximum Light Recieved at the Detector. (2)
1 - 90 Degrees Clockwise
2 - 270 Degrees Anticlockwise
58
2 Polarising Filters are placed between a Source and a Detector, Parallel to each other.
State the Rotations of both 1+2 for Maximum Light Recieved at the Detector. (3)
1 - 90 Degrees
2 - 270 Degrees
Both in the Same Direction.
59
State the Method and Observations of the Double-Slit Experiment. (5)
-A Beam of Electrons are fired at 2 Slits, one at a time.
-Expected to see 2 Lines of Impact on the Screen.
-Saw an Interference Pattern.
-A Measuring Device is Placed at the Slits.
-Saw 2 Lines of Impact on the Screen.
60
Explain the Explanation for the Double-Slit Experiment. (5)
-Electrons behave as Waves as they go through the Slits.
-Each Electron goes through 1 Slit, Both and Neither at the Same Time.
-The Electron Interferes with itself and Produces an Interference Pattern with Itself.
-The Electron's Position is measured at the Screen where it Lands in 1 Place.
-Over Time the Electron's Impact Builds-up an Interference Patternon the Screen because we can Imagine the Electron 'Wave' as a Probability of where it will Land.
-When Observed at the Slit, the Wave Function is Collapsed and so the Electron only Passes through 1 Slit and No Interference Pattern Occurs.
61
State de Broglie's Hypothesis.
All Particles have a Wave and Particle Nature.
62
State the de Broglie Equation.
Wavelength = h/p
63
State what h Represents in the de Broglie Equation.
Planck's Constant
64
State what p Represents in the de Broglie Equation.
Momentum of the Particle.
65
Wave Behaviour at Interference
66
Pulse-Echo Technique
67
What does the Photon Model State about EM Waves?
EM Waves travel in Discrete Packets called Photons which have Energy Directly Proportional to their Frequency.
68
What does the Wave Model State about EM Waves.
EM Radiation can be described as a Transverse Wave.
69
Photon Energy is Directly Proportional to their....
Frequency
70
State the Photon Energy Equation.
E= hf
71
State what h Represents in the Photon Energy Equation.
Planck's Constant
72
Define the Photoelectric Effect. (2)
-When Light of a High enough Energy shone on a Metal Surface causes
Electrons to be Emitted.
-The Electrons are given enough Kinetic Energy by the Photons to overcome the Attractive Force of the Ions in the Metal.
73
Define Threshold Frequency.
The Minimum Frequency of Light needed to cause Electrons to be Emitted in the Photoelectric Effect regardless of the Intensity.
74
State why Photoelectrons are Emitted from a Metal Surface.
Electrons near the Surface of a Metal Absorb a Photon and Gain enough Energy to leave the Surface.
75
Define Work Function.
The Minimum Energy required to just Liberate an Electron from the Surface
of a Metal.
76
Explain the Method and Observations of the Stopping Voltage Experiment. (7)
-A Photoanode and a Cathode are set up in a Vaccum Tube. with the Cathode being Wired to the Anode externally using an Ammeter.
-Light is Incident on the Photoanode and the Photoelectric Effect Occurs.
-Photoelectrons Crossing the Gap complete the Circuit and then Travel around the Wire back to the Photoanode, so a Photocurrent is measured on the Ammeter.
-A Power Supply is Introduced into the Circuit.
-The Voltage is Increased Against the Flow of Electrons until the Photocurrent is reduced to 0.
-The Lowest Voltage this Achieves is called the Stopping Voltage.
-The Frequency and Hence Wavelength of Incident Light and the Experiment is repeated.
77
Explain the Analysis of the Stopping Voltage Experiment. (8)
-Photoelectric Equation
-The Photocurrent is 0 when Ek(max) is 0, so no Photoelectrons Crossing the Gap.
-This happens when Work is Done Against the Electrons: Ek(max) = W
- W=VQ so Ek(max) = W =Ve
-Ek(max) = hf - Work Function
-Ek(max) / e = hf / e - Work Function / e
-V = hf/e - Work Function/e
-Plot a Graph of Stopping Voltage aginst Frequency, where the x-intercept in the Threshold Frequency, the Gradient is h/e and the y-intercept is Work Function/e, so the Magnitude of the y-intercept is Work Function in eV.
78
State the Photoelectric Equation.
E = hf = Work Function + Ek (max)
79
Define ElectronVolt.
The Kinetic Energy gained by one Electron that is Accelerated through a Potential Difference of 1 Volt.
80
State how to Convert between Joules to ElectronVolts.
Divide by 1.6x10^-19
81
State how to Convert between ElectronVolts and Joules.
Multiply by 1.6x10^-19
82
Explain the Method and Observations from the Photoelectric Effect Experiment. (6)
-A Piece of Zinc with a Gold Leaf is attached is Negatively Charged inside a Gold Leaf Electroscope and Insulated from the Environment.
-The Leaf Rises away from the Central Zinc Pin.
-Light of Varying Wavelengths and Intensities is Shone on the Zinc Plate at the Top of the Electroscope.
-Light below a Certain Frequency has no effect whatever the Intensity.
-UV Light makes the Gold Leaf Fall, showing it Loses Charge.
-This happens at High and Low Intensity, but Faster at High Intensity.
83
Explain the Explanation for the Photoelectric Effect Experiment. (8)
-If Incident Light on the Zinc was a Wave:
The Leaf should fall as Energy is Absorbed. (Doesn't Happen)
Increasing the Intensity should Increase KE and hence the Speed of Escaping Photoelectrons. (Doesn't Happen).
-Instead, Light acts as a Photon and every Photon is absorbed by an Electron.
-Photon Energy = hf
-A Single Photon must have enough Energy to overcome the Work Function or have a Frequency greater than the Threshold Frequency for the Material.
-If Photon Energy is Greater than the Work Function, an Electron Escapes and the Leaf loses Charge.
-Higher Intensity means more Photons per Second, so will do nothing if the Energy is less than the Work Function but will Liberate more Electrons per Second.
84
State where in an Atom Electrons are Situated.
Discrete Energy Levels.
85
State what happens when an Electron Gains enough Energy. (2)
-It Moves up an Energy Level.
-Excitation.
86
State what happens after Excitation of Electrons.
Electrons Quickly return to its Original Energy Level to release the Energy it gained in the form of a Photon of Light.
87
Explain the Method and Observations of the Energy Levels and Line Spectra Experiment. (6)
-Shine the Light from a Black Body Radiator through Hydrogen Gas.
-Seperate out the Light via a Spectroscope.
-Observe the Full EM Spectrum present Except a few Black Lines at Specific Wavelengths (These are Absorption Lines).
OR
-Excite a Gas (Mercury) with Incident Energy.
-Seperate the Light out with a Spectroscope.
-Observe a Few Discrete Wavelengths of the Colour given off. (These are Emission Lines).
88
Explain the Explanation for the Energy Levels and Line Spectra Experiment. (5)
-The Lines have a Wavelength that Corresponds to the Difference in Energy Levels for the Material they went through.
-Photon Energy Released = hc/Wavelength
-Difference in Energy Levels = E2-E1
-For Absorption Lines it Represents Excitation.
-For Emission Lines it Represents De-Excitation.
89
State the Eqaution for Calculating the Photon Frequency.
f = E1-E2/h
90
Define Mechanical Wave.
Waves that require a Medium to Oscillate in the Direction of Energy Transfer and are Genertated by Vibrating Sources.
91
Define Electromagnetic Waves.
Waves created when Charged Particles are Accelerated and they don't require a Medium for Transmission.
92
Name the types of Waves in the Electromagnetic Spectrum from Longest to Shortest Wavelength. (7)
Radio
Micro
Infrared
Visible
Ultraviolet
X-ray
Gamma
93
State a Use of Radio Waves.
-TV/Radio Signals
94
State 2 Uses of Microwaves.
-Cooking Food
-Satelite Communications
95
State 2 Uses of Infrared Waves.
-Electric Heaters
-Infrared Cameras
96
State a Use of Visible Light Waves.
-Fibre Optic Communications
97
State 2 Uses of UV Waves.
-Medical Treatments
-Sterilisation
98
State a Use of Gamma Rays.
-Information Processing
99
State the Danger of using Radio/Micro/Infrared Waves.
Waves can Penetrate the Body and cause Burns and Organ Failure.
100
State the Danger of using Visible Light Waves.
High Exposure can damage the Retina.
101
State the Danger of using UV Waves.
High Exposure acn cause Skin Burns and Cancer.
102
State the Danger of using X-rays and Gamma Rays.
High Exposure of Ionising Radiation can Mutate Genes and lead to Cancer Development.
Edexcel A-Level Physics
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