dispersion of light, scattering of light, subtraction of light (note)

8.5 DISPERSION OF LIGHT

Why? Copy title only , no need to draw

How?

1.White light – consists of 7 colours RED
2.Different colour, different speed
3.Higher speed, less refracted - Highest speed
- least refracted

VIOLET

- Lowest speed
- Most refracted

1. During the Copy sentences only, no need to draw
heavy rain,
there are a lot
of rain water
droplets
floating in the
sky.

2. Sunlight Copy sentences only, no need to draw
entering the
droplets of
rain water will
be refracted
and dispersed
into the seven
colours of
light.

The seven colours Copy sentences only, no need to draw
of light are
reflected and
refracted out of the
rain water droplets
into the air to form
a spectrum of
sunlight known as a
rainbow.

BLUE8.6 SCATTERING OF LIGHT

(midday)

- Air particles smaller than wavelength of visible light
- most effective scatterers of shorter wavelength (blue)
- Blue light→ scattered the most in all directions
- THEREFORE, SKY LOOKS BLUE

8.6 SCATTERING OF LIGHT RED

(sunset)

- Atmosphere →thick (sun at horizon)
- Shorter wavelengths (blue) are scattered away
- Only red light (less scattered) reaches our eye
- THEREFORE, SKY LOOKS RED

8.7 ADDITION AND SUBTRACTION OF LIGHT

COLOURED LIGHT→ Can be categorized into 2 types

Produced when all • Basic colour
3 primary colours • Cannot produced by
mixed together
colour mixing

• produced from mixing of 2 colours

THE SUBTRACTION OF LIGHT

Why do we see banana
as yellow?

The same colour light (with opaque
objects) will be reflected directly
into our eyes

OTHER COLOURS?
Will be absorbed by the objects

Object with secondary
colours will reflect the
light which has the same
colours as them and
primary colours which

form them





DIFFERENCE BETWEEN
ADDITION AND SUBTRACTION OF LIGHT

Mixing of primary Occur when opaque
colour lights to object reflects the
light of same colour
produce secondary
colour lights and absorb the
other colour

EXAMPLES OF ADDITION AND SUBTRACTION OF LIGHT

Colour television

Coloured light

in a stadium Coloured light

Coloured light at KLCC

on stage