p2:waves - Refraction Flashcards

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1
Q

what happebs to wavefront as they enter a medium
what happens to frequency of light

A

slow down
stays the same

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2
Q

what happens when light goes from less dense to more dense

A

light bends towards the normal

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3
Q

what the equations for refraction (3)

A

sin(I)/sin(r) = n2/n1 = v1/v2

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4
Q

what does n equal in that eqaution

A

fractional index of material

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5
Q

what does v = in that euqaaiton

A

speed of ligt in material

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6
Q

whats the refractional indexc of air/vacum
and glass

A

air/vaccum = 1
glass = 1.6

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7
Q

what happens when light goes down the normal

A

doesn’t refract

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8
Q

what is the critical angle

A

when light refracts at 90 degrees the angle of incidence is called thecritivcal angle(light refracted along the boundary)

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9
Q

what conditions do we need for the critical angle to work

A

more dense to less dense

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10
Q

whats the equation for snells law(critical angle)

A

sin c/sin(90) = n2/n1

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11
Q

what is total interrnal reflection

A

when the angle of refraction is bigger than the critical angle light is not refracted but reflected

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12
Q

how does a fibre optic cable work

A

uses a total internal reflection to transfer information

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13
Q

what do we put on fibre optic cables and how does it help

A

cladding
protects inner fibre form damage
prevents cross talk

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14
Q

what causes material dispersion

A

white light being hsone inot cables
different wavelengths of light travel at different speeds

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15
Q

name 2 ways of material dispersion

A

pulse broadening
modal dispersion

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16
Q

how does pulse broadening affect fiber optic cables(2 things)
and how is it caused

A

signals of light sent in 1s and 0s
spreads pulses which limit the maximum frequency
causes bandwidth availability to decrease

17
Q

how do we counter pulse broadening(3 things)

A

use monochromatic light
booster stations
increase amplitude

18
Q

how does modal dispersion affect fibre optic cables and how is it caused

A

light taking different paths - causes light to come out at different times
causes pulse broadening

19
Q

how do we counter modal dispersion(3 things)

A

using a core
and booster stations
increase amplitude