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Physics - Topic 5 - Waves And Particle Nature Of Light > Topic 5 - Spec - Waves and Particle Nature of Light > Flashcards

Topic 5 - Spec - Waves and Particle Nature of Light Flashcards

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1
Q

Define the term Amplitude.

A

The maximum magnitude of displacement (measured in metres/m)

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2
Q

Define the term Frequency.

A

The number of cycles (vibrations) per second passing a given point.

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3
Q

Define the term Period.

A

The time taken for a whole cycle (vibration) to complete

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4
Q

Define the term Wave Speed.

A

Is the speed at which a wave travels.

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5
Q

Define the term Wavelength.

A

The length of one whole wave cycle (crest to crest / trough to trough) measured in Metres/m

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6
Q

What is the Wave Equation?

A

v = fλ v = speed of wave f = Frequency λ = Wavelength

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7
Q

What is a Longitudinal Wave?

A

Is a wave vibrating in the direction of travel, made up of Compressions (high pressures) and Rarefactions (low pressures)

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8
Q

What is the difference between molecule displacements in Longitudinal Waves?

A

In Compressions - The molecules are closer together increasing the pressure at that point

In Rarefactions - The molecules are further apart decreasing the pressure at that point.

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9
Q

Describe a Transverse wave.

A

Are waves that vibrate at right angles to the direction of travel, all Electromagnetic Waves are Transverse.

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10
Q

How do you draw a Longitudinal Wave Graphically? PLEASE DO NOT CONFUSE WITH TRANSVERSE

A

Difference is, is that Density is on the Y-Axis and Time is on the X-Axis

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11
Q

How do you draw a Transverse Wave on a Graph?

A
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12
Q

CORE PRACTICAL - Determine the speed of sound in air using a 2-beam oscilloscope, signal generator, speaker and microphone.

A

1 - Set up the apparatus and set the frequency of the signal generator to around 2.6Hz

2 - Adjus the gain dials of each input and the timebase so you can see one cycle wave cycle.

3 - Change the distance between the microphone and loudspeaker so that the peaks of one wave line up with the troughs of the other wave then measure the distance between the loudspeaker and microphone.

4 - Calculate the frequency by measuring the Period, using f = 1/T measuring frequency this way gives us a smaller uncretainty.

5 - Move the microphone away from or towards the loudspeaker so that the microphones corresponding wave on the oscilloscope moves one full wavelength, measure the new distance between the microphone and loudspeaker.

6 - The difference in the two record distances is the wavelength of the sound wave

7 - Repeat this process to find a mean value for the distance moved by the microphone, use v = fλ

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13
Q

Explain what is meant by a Wavefront.

A

Is a line joining points at the same position along a wave.

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14
Q

Explain what is meant by Coherance.

A

They have the same wavelength and frequency and a fixed phase difference between them.

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15
Q

Explain what is meant by Path Difference

A

Is the amount by which the path travelled by one wave is longer than the path travelled by the other wave.

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16
Q

Explain what is meant by Superposition.

A

A complex wave can be separated out mathematically into several simple sine waves of various sizes.

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17
Q

Explain what is meant by Interference.

A

Is the effect created when two or more waves superpose with each other.

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18
Q

Explain what is meant by Phase.

A

Two waves with the same frequency are “in phase” if they have the same phase and therefore line up everywhere.

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19
Q

What is the relationship between path difference and phase difference?

A
  • A path difference of nλ (n is an integer) will lead to a Constructive Interference.
  • A path difference of (n + 0.5)λ will lead toa destructive interference.
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20
Q
A
21
Q

Explain what is meant by a Stationary Wave.

A

is the superposition of two progressive waves with the same wavelength, moving in opposite directions.

22
Q

How are Stationary / Standing Waves formed?

A
23
Q

What are Nodes and Anti-Nodes? Show them on a Wave?

A

Node - is a point along a standing wave where the wave has minimum amplitude/Zero Amplitude.

Anti-Node - is a point where the amplitude of the standing wave is at maximum.

24
Q

What is the equation for the speed of a transverse wave on a string?

A

v = √T / μ

v = speed of wave (m s*-1)

T = Tension (N)

μ = Mass per unit Length (kg m*-1)

25
Q

CORE PRACTICAL - Investigate the effects of length, tension and mass per unit length on the frequency of a vibrating wire.

A

1 - Set up the apparatus

2 - Measure the mass (M) and length (L) of the string, then use μ = M/L to find the mass per unit length μ (kg m*-1)

3 - Then use the apparatus to calculate the tension in the wire using T = mg, also record the length of th wire.

4 - Turn on the signal generator and vary the frequency until you find the first harmonic, record the frequency of the first harmonic.

5 - The wavelength of the wave is found by using the equation λ = 2L to calculate the frequency use f = v / λ substitute in the equations to make f = 1 / 2L √T / μ

INVESTIGATE HOW LENGTH, TENSION OR MASS PER UNIT LENGTH AFFECTS THE FREQUENCY OF THE STRING

  • Keep the string type, and tension the same and alter the length, find the first harmonic again and record f against L.
  • Keep the string types and length the same add or remove masses, find the first harmonic agiain and record f against T.
  • Keep the length and tension the same but using different string samples to vary μ, find the first harmonic and record f against μ
26
Q

What is the equation for intensity of radiation?

A
27
Q

What is Snells Law?

A

n1sin(i) = n2sin(r)

n1 = Incident material Refractive Index

sin(I) =

28
Q

What is the speed of light?

A

3.0 x 10*-8

29
Q

What is the Refractive Index Equation?

A
30
Q

What is the process of Refraction?

A
31
Q

What is the equation to find the Critical Angle?

A

sin(C) = 1 / n

32
Q

How do we predict whether total internal reflection will occur at an interface?

A
33
Q

Understand how to measure the Refractive index of a solid material.

A

1 - Place a glass block on a piece of paper and draw around it

2 - Use a Ray box to shine a beam of light into the glass block, Keep the room DARK.

3 - Trace the path of the incoming and outgoing rays either side of the block

4 - Remove the block and join up the two paths you have drawn with a straight line, to show the change of the lights path within the box.

5 - Measure the angle of incidence (sin(I)) and the angle of reflection (sin(r))

6 - Rearrrange Snells Law to make the Refractive index of the material the subject, remember the Refractive index for air = 1

34
Q

What is meant by Focal Length (f)?

A

Is the distance between the lens axis and the focal plane.

f is positive for a converging lens because it is in front of the lens and is negative for a diverging lens because it is behind the lens.

35
Q

How do you use a Ray with a Converging lens?

A
  • Draw 2 rays from the same point on the object
36
Q

How do you use a Ray Diagram with a Diverging lens?

A
  • A diverging lens will always form a virtual image

-

37
Q

What is the equation for the Power of a Lens?

A

P = 1 / f

P = Power (measured in Dioptres, D)

f = focal length

38
Q

Show the equation the relates f, u and v and only works for THIN LENSES.

A

1 / f = 1 / u + 1 / v

f = Focal Length

u = distance between object and lens axis

v = distance between image and lens axis

remeber focal length is positive for a Converging Lens and negative for a Diverging Lens

39
Q

What is the Power equation for lenses in combination?

A

P = P1 + P2 + P3

40
Q

What is a Virtual Image?

A
41
Q
A
42
Q

What is a Real Image?

A
43
Q

What is the Magnification equation?

A

Magnification = Image height / Object height

m = v / u

44
Q

Understand what is meant by Plane Polarisation.

A

is the process of polarising a wave so that it only oscillates in one direction.

45
Q

What is meant by Diffraction?

A

Is the bending of waves when they pass through a gap, or curve around edges.

46
Q

Use Huygen’s Construction to explain what happens to a wave when it meets a slit or an obstacle.

A

every point on a wavefront may be considered to be a point source of secondary wavelets that spread out in the forward direction at the speed of the wave. The new wavefront is the surface that is tangential to all of these secondary wavelets.

47
Q

What is the equation for Diffraction Gratings?

A

d sin(θ) = n λ

sin (θ) = Angle of diffraction

d = distance between slits

λ = wavelength of the light

n = order of diffraction

48
Q

CORE PRACTICAL -

A

Physics - Topic 5 - Waves And Particle Nature Of Light (6 decks)

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