Colours, Reflection, Refraction

Dispersion

is when a white light splits into its components. it happens because different colours slow down and refract by different amounts

Colours that make white

red, orange, yellow. green, blue, indigo, violet

Opaque objects properties

reflect their own colour and absorb the rest

Transparent and translucent object properties

transmit their own colour and absorb the rest

what happens if you put white light through a orange filter

all other colour will be absorbed except orange

Rods

see in black and white and tell us the shape of an object. they allow us to see in the dark

Cones

sense colour and they need more light than rods to work well

Why is the sky blue

molecules in the atmosphere scatter blue and violet light. We see the sky as more blue because synths contain more blue light and our eyes are more sensitive to blue

Law of reflection

angle of incidence = angle of reflection

Plane mirror

flat, smooth mirror

Properties of an image formed by a plane mirror

same distance, same size, image is inverted, rays of light do not come from it

Refraction

is the change in direction of a wave at a boundary

Formula for refractive index

sin i : sin r OR speed of light in a vacuum : speed of light in medium

cornea

transparent lens that refracts light

iris

controls how much light enter the pupil

lens

transparent disc that can change shape to focus light into the retina

retina

contains rods and cones

optic nerve

sensory neurone that carries impulses between eye and the brain

pupil

hole that allows light to enter the eye