Y1 Ch 05 Waves Flashcards

1
Q

Progressive Wave definition

A

An oscillation or vibration that transfers energy and information not matter.

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2
Q

Frequency definition

A

The number of cycles or vibrations per second, measured in Hertz

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3
Q

Period definition

A

Time per cycle, measured in seconds

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4
Q

Amplitude definition

A

The maximum displacement from the equilibrium line

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5
Q

Wavelength definition

A

The distance between wake peaks or two equivalent points

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6
Q

Longitudinal wave definition

A

A wave where the oscillation is parallel to the direction of travel

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7
Q

Transverse wave definition

A

A wave where the oscillation is perpendicular to the direction of travel

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8
Q

Phase difference definition

A

the fraction of a wave cycle between two points

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9
Q

Phase difference equation

A

2pidistance between the two points/wavelength

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10
Q

Polarisation definition

A

the action of restricting the vibrations of a transverse wave, especially light, wholly or partially to one direction

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11
Q

Polarisation only happens to …..

A

transverse waves

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12
Q

How can Light be polarised?

A
  1. Reflection 2. filters 3. through certain materials
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13
Q

Why is polarisation used?

A
  1. to reduce glare 2. to reduce interference
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14
Q

Refraction explanation

A

as a wave travels from one material to another it will change speed causing it to change direction

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15
Q

Refractive index equation

A

n = C/Cs

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16
Q

Refractive index definition

A

The ratio of a wave’s speed in a vacuum to the wave’s speed in the substance

17
Q

Snells law

A

N1 * Sinϴ1 = N2 * Sinϴ2

18
Q

Which has a longer wavelength red light or blue light?

19
Q

Total Internal Reflection Definition

A

when all light is reflected off a boundary of 2 materials if different optical densities

20
Q

For TIR to occur the angle of incidence must be bigger than the …

A

Critical angle

21
Q

How to find the critical angle

A

Sinϴ = 1/n1

22
Q

What occurs inside an optic fibre so light can be transferred

A

Total Internal Reflection

23
Q

Why is there cladding on an optic fibre

A
  1. to increase the surrounding refractive index so only light with a shallower path can be reflected 2. to stop light leaking out when the core is damaged
24
Q

What must the refractive index of the cladding of an optic fibre be in terms of the refractive index?

A

Bigger than air but smaller than the core so it can totally internally reflect

25
Broadening (optic fibres)
The dispersion of pulses - too much broadening causes a reduction in the quality of the signal
26
Pulse broadening limits ...
the frequency of pulses sent down an optic fibre
27
What do we do to overcome the material absorbing the light energy?
amplify the signal