M4 Refraction Flashcards

snell's law refractive index TIR

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1
Q

Why does light refract

A

When light enters a more dense substance at an angle, the particles hit the substance at different times meaning it bends towards the normal and slows down

If it goes into a less dense substance it bends away from the normal and speeds up

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2
Q

What is the first law of refraction

A

At the point where the light hits the substance, the incident ray, reflected ray and normal lie on the same plane

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3
Q

In the equation n=c/v what do the letters stand for

A

n is refractive index
c is speed of light through a vacuum, 3 X 10^8
v is the speed of light through the material

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4
Q

In the equation nsinθ=k

What do all the symbols mean

A

n is the refractive index
θ is the angle between the normal and incident ray
k is the constant

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5
Q

What equation can you use when light travels from one medium to another

A

n1sin(θ1) = n2sin(θ2)

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6
Q

If light enters a glass block from air at an angle of 30 degrees what is the angle of refraction

Refractive index of air is 1
Refractive index of glass is 1.5

A

1sin30 = 1.5sinθ

1/3 = sinθ
θ = 19.5 degrees
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7
Q

what happens if the angle of incidence is smaller than the critical angle

A

the light ray is refracted

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8
Q

what happens if the angle of incidence equals the critical angle

A

the light ray is refracted along the boundary

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9
Q

what happens if the angle of incidence is greater than the critical angle

A

the light ray is NOT refracted and total internal reflection occurs

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10
Q

what is TIR

A

total internal reflection
occurs at the boundary between 2 different media
when light strikes the boundary at a larger angle than the critical angle
all light is reflected back into the original medium and no light is refracted out of the original medium

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11
Q

what are the conditions for TIR

A

angle of incidence needs to be larger than the critical angle
rays must travel from a more dense to a less dense medium

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12
Q

what does the equation sinc = 1/n mean

A

to calculate the critical angle for material to air boundary

sin of the critical angle = 1 / refractive index

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13
Q

why do we use a semi-circular block rather than a rectangular block in the experiment to determine the critical angle

A

so incident ray enters at 0 degrees

so refraction occurs inside the block

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14
Q

draw a diagram of TIR happening inside a prism

A

look it up

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15
Q

in refraction what happens if

a) the angle of incidence is smaller than the critical angle?
b) the angle of incidence equals the critical angle?
c) the angle of incidence is bigger than the critical angle?

A

a) the ray is refracted and partially reflected
b) the ray is refracted along the boundary and partially reflected
c) total internal reflection

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