Light Flashcards
Speed of light in a vacumm
300,000 km/s
Light…
carries energy as a wave, travels in straight lines. Can travel through any medium as long it lets light through
How are objects that emit light called
luminous
Law of reflection
when a ray of light reflects off a surface, the angle of incidence is equal to the angle of reflection
Angle of incidence
The angle at which light hits an object
Angle of reflection
The angle at which light bounces off an object, equal to the angle of incidence
Normal
the perpendicular line to the surface light bounces off
Regular Reflection
Any surface that produces a reflected image
Diffuse reflection
A surface we can see but does not produce a reflection
Refraction
When light crosses the boundary between two mediums, light slows down or speeds up. This change of speed can result in a change of direction
Light slows down,
Enters a denser medium and bends towards normal
Light speeds up,
Enters a less dense medium and bends away from normal
Light hits barrier at 90º exactly…
Slows down but does not change direction
Total Internal Reflection (TIR)
Only happens when light is travelling from a denser to a lense dense medium, the ray must strike the boundary at an angle greater than the critical angle
Angle i is less than the critical angle =
Refraction
Angle i is equal to the critical angle =
Light along boundary
Dispersion
The separation of visible light into its different colours
Colour spectrum
Red, Orange, Yellow, Green, Blue, Indigo, Violet
Colours are…
Different colours of light have a different frequency.
Red - Low
Violet - High
Seeing Things
The layer at the back of the eye(Retina) converts light into nerve impulses
Rods
Detect the amount of light, see in black and white. Works best in dark
Cones
Detect the frequency of light(can see colours). Works best in bright light
Primary colours
If you mix them together you will get white light.
Red, Green and Blue.
Secondary Colours
Yellow, Magenta and Cyan. Produced by two primary colours
Red + Green –>
Yellow
Blue + Red –>
Magenta
Green +`Blue –>
Cyan
Filter
A colour filter works by absorbing a certain colour and transmitting the other colour
Colour of things
If something is yellow it will absorb all colours but yellow and reflect it. Therefore you will see it yellow(red + green)
