3.1 Longitudinal & Transverse Waves Flashcards

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1
Q

What is a progressive wave defined as?

A

A wave that transfers energy from one point to another without transferring the medium itself

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2
Q

What are the properties of a progressive wave? (6(

A
  • displacement
  • amplitude
  • wavelength
  • time period
  • frequency
  • speed
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3
Q

What is the displacement of a wave?

A
  • distance of a point on the wave from its equilibrium position
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4
Q

What is the Amplitude of a wave?

A
  • the maximum displacement of a particle in the wave from its equilibrium position
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5
Q

What is the wavelength of a wave?

A
  • the distance beterrn points on successive oscillations of the wave
  • measured in metres
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6
Q

What is the time period of a wavE?

A
  • the time taken for one complete oscillation or cycle of the wave
  • measured in seconds
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7
Q

What is the frequency of a wave?

A
  • the number of complete oscillations per unit time
  • measured in Hertz
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8
Q

What is the equation for frequency?

A

frequency = 1/time period

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9
Q

What is the speed of a wave?

A
  • the distance travelled by the wave per unit time
  • (metres per second)
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10
Q

What is the wave equation?

A

speed of a wave = frequency x wavelength

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11
Q

What does the wave equation show?

A

as the wavelength increases, the frequency decreases and vis a versa

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12
Q

What is phase difference?

A

the phase difference between two waves is a measure of how much a point or wave is in front or behind another

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13
Q

how can you find the phase difference?

A
  • the relative position of the crests or troughs of two different waves of the same frequency
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14
Q

What determines whether 2 waves are in or out of phase?

A
  • when crests and troughs are aligned in phase
  • when crest of one wave aligns with the trough of another they are in anti phase
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15
Q

How can the phase difference be calculated?

A
  • from 2 different points on the same wave
  • same point on 2 different waves
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16
Q

How can phase difference be measured?

A
  • fractions of a wavelength
  • degrees
  • radians
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17
Q

if a wave is in phase, how can it be described?

A
  • 360 degrees
  • 2π radians
18
Q

if a wave is in anti-phase, how can it be described?

A
  • 180 degrees
  • π radians
19
Q

What are the 2 types of waves?

A
  • transverse
  • longitudinal
20
Q

How can you determine what type of wave a wave is?

A

by the direction of the oscillations in relation to the direction the wave is travelling

21
Q

What is a transverse wave?

A

a wave in which the particles oscillate perpendicular to the direction of the wave travel and energy transfer

22
Q

What are the properties of transverse waves?

A
  • show areas of crests and troughs
  • can be shown on a rope
  • can be polarised
23
Q

What are 2 examples of transverse waves?

A
  • electromagnetic waves
  • vibrations on a guitar string
  • waves on a string
  • seismic waves
24
Q

Longitudinal wave is defined as:

A

a wave in which the particles oscillate parallel to the direction of the wave travel and energy transfer

25
Q

What are some characteristics of longitudinal waves?

A
  • shows areas of compressions and rarefactions
  • shown on a link spring
  • cannot be polarised
26
Q

How is energy transmitted in a longitudinal wave?

A
  • the medium vibrating as they are given energy
  • compressions cause the nearby particles to also vibrate with more energy
  • produces a compression further along in the medium
27
Q

What are examples of longitudinal waveS?

A
  • sound waves
  • ultrasound waves
  • waves through a slinky
  • seismic waves
28
Q

What are compressions of a wave?

A

regions of increased pressureW

29
Q

What are rarefactions of a wave?

A

regions of decreased pressure

30
Q

What is polarisation?

A

when particles oscillations occur in only one of the directions perpendicular to the direction of wave propagation

31
Q

Why can polarisation only occur in transverse waves?

A

because transverse waves oscillate in any plane perpendicular to the propagation direction

32
Q

What does it mean when transverse waves are polarised?

A
  • vibrations are restricted to one direction
  • vibrations here are still perpendicular to the direction on propagation/energy transfer
33
Q

Why can longitudinal waves not be polarised?

A
  • they oscillate parallel to the direction of travel
34
Q

How can waves be polarised?

A

through a
- polariser
- polarising filter

35
Q

How do polarisers work?

A

they only allow oscillations in a certain plane to be transmitted

36
Q

what are some examples of polarisation?

A
  • sunglasses
  • photography
  • radio and microwave signals
37
Q

How do polaroid sunglasses work?

A
  • they contain lenses with filter transmission axes that are vertically oriented
  • the glasses don’t allow any horizontal polarised light to pass through
  • when light is reflected from a surface it undergoes partial polarisation
  • thus the glasses reduce the glare on the surface allowing things to be viewed more clearly
38
Q

What is partial polarisation?

A

if the surface is horizontal, a proportion of the reflected light will oscillate more int he horizontal plane than in the vertical plane

39
Q

How does Polaroid Photography work?

A
  • work in the same way as glasses
  • allow photographers to take photos of objects underwater
40
Q

How can polaroid cameras take photos underwater?

A
  • light reflected on the surface of the water is partially polarised in the horizontal plane
  • the glare is eliminated by the polarising lens
  • light from underwater objects is refracted by the surface of the water thus not plane polarised
  • thus the light from the underwater object is more intense than the glare and how’s up much more brightly in the photo
41
Q

How does polarisation of radio and microwave signals occur?

A
  • radio and television services are broadcast either horizontally-polarised or vertically-polarised
  • the reception aerial needs to be mounted flat or on its side
  • the orientation of the aerial wall depend on the transmitter it is pointing towards and the polarity of the services being broadcast
42
Q
A