refraction of light

refraction

The bending of a wave as it passes at an angle from one medium to another
some of the light ray will be reflected and some of it will be absorbed

less dense to more dense medium

the angle of refraction will be smaller than the angle of incidence and bend towards the normal

more dense to less dense medium

light ray will bend away from the normal and angle of refraction will be bigger than angle of incidence

Snell's law

refractive index

refractive index = v vacuum / v in a medium

speed of light in vacuum = 3 X 10 ^8 ms-1

Angles measured

clockwise

anticlockwise

clockwise direction -
anticlockwise direction +

apparent depth

The depth that an object appears to be at

due to the refraction of light in a transparent medium

Lateral displacement

s = d sin (i - i') / cos i'

incident ray and emergent ray are parallel

lateral displacement of light ray = its displacement sideways when going from 1 medium to the other

light ray entering a glass block

light ray will bend 10 degrees towards normal (air to glass)
when leaving the block the light ray will bend 10 away from the normal (glass to air)
the light doesn't have any overall bending

principal of resistibility

if light rays was travelling through glass block in the opposite direction

it would bend and move outward by the same amount as well

prism

the surfaces are not parallel

prism ocular health

use to relieve defects caused by extraocular muscle dysfunction

paraxial equation

L = n / l
n= refractive index
l = distance (m)

n' - n / r = n/l = n’/l'