Spectral Dispersion

OP36 recall that white light is made up of different colours .

OP37 produce a spectrum of white light using appropriate apparatus, and list the colours of the spectrum

  • Richard
  • Of
  • York
  • Gave
  • Battle
  • In
  • Vein

There are really only 6 Colours in the rainbow.

Newton created the 7th to please himself and his opinions on nature.

Since most people believed what he said, this was accepted and is considered to be true now!

He wanted seven colours, one for each day of the week, the number of known planets at the time and the number of notes in the major musical scale.

Light is made up of many colours

Light box & (RGBYMC) gels .... show the mixing of light,

use side wing mirrors and introduce reflection.

Or use LEDS get !

which can be separated by dispersion

  • Rainbow
  • Oil in puddle
  • Leaded glasses
  • Beveled windows
  • Through a prism

To show dispersion of white light through a prism


glass prism, ray box, power supply unit, dark room, graph paper, pencil, protractor.

  1. place prism on graph paper

The Alternative Demonstration Method

  1. set up ray box at the lowest working voltage
  2. turn on
  3. point ray of light at prism
  4. darken room
  5. rotate the prism
  6. locate the spectrum
  7. maximise the spectrum,
  8. sketch the outline of the prism, the ray in, the spectrum out
  1. Using a OHP, place 2 sheets of black card on the bed of the projector
  2. make a small gap between them
  3. place a prism in the mirror flap, or use a retort stand,
  4. line up the beam so it comes through the prism
  5. carefully rotate the prism so the dispersion comes out on the screen.