light

When light hits an object, some will be _____, _____, or _____.

Reflected, transmitted, or absorbed

how much light will be transmitted in a transparent object?

lots

how much light will be transmitted in an opaque object?

very little

what is the law of reflection?

angle of incidence = angle of reflection

i=r

how do regular reflections work?

parallel incident rays give parallel reflected rays

clear image

how do diffuse reflections work?

parallel rays of light are not reflected parallel

no clear image

what happens when light goes from a less optically dense to a more optically dense material?

light bends towards the normal

what happens when sound goes from a more dense material to a less dense material?

bends towards normal

in more optically dense materials, light travels…

slower

slowing down of light means…

light bends towards the normal

slowing down more means…

more bending

what is the refractive index of a vacuum?

1

equation for refractive index?

speed of light in a vacuum / speed of light in material = refractive index

equation for refractive index (involving sin) when light enters an object?

n (refractive index) = sin i / sin r

equation for refractive index (involving sin) when light is leaving an object?

n = sin r / sin i

total internal reflection

all the light is reflected inside the material (block)

for the following questions, assume light is leaving a block into air. What happens when light leaves a block into air?

bends away from the normal

what happens if we increase the angle of incidence?

angle of refraction increases

what is the critical angle?

the angle of incidence that gives r=90

the largest angle where refraction still happens

what are the conditions for TIR to occur?

go from more dense to less dense

i>c (critical angle)

inside a solid block

uses of total internal reflection

prisms in: periscopes, binoculars, reflectors (bikes, cars), retroreflector (cats eyes)

fibre optics for communication

jewellery

equation linking refractive index and sin c

n = 1 / sin c

why are diamonds really sparkly

diamonds have a high refractive index, so a small critical angle

there are a lot of angles between c and 90

greater chance that i>c so more TIR