Spectrum D. Crowley, 2008

Spectrum To know how a spectrum (rainbow of colours) is made

Colours What are the colours of the rainbow? Can you make a rhyme to remember them? Red Orange Yellow Green Blue Indigo Violet Richard Of York Gave Battle In Vein

Dispersion White light can be split up to form a spectrum by using a prism (a triangular block of transparent material) Shine a ray of bright white light at a prism and move the prism until colours appear – draw a diagram showing what you have observed

Dispersion (Splitting Light) A prism splits a ray of white light into a spectrum of colours, known as dispersion

Waves What is the difference between each colour of the spectrum? Each colour has a different wave length ( ) Blue Green Red

Dispersion Why do the colours appear after they have travelled through a prism?! The different colours of light have different wavelengths, this means they are bent (refracted) by different amounts - which colour is refracted the most? Red light is refracted least because it has the longest wavelength Violet light is refracted the most because it has the shortest wavelength

Dispersion Light can be dispersed to give a spectrum of colours (using a prism) Your challenge is to recombine this dispersed light – how could you do this?

Newton’s Disc Spinning the disc quickly combines all the wavelengths of light – making white light via colour addition

Newton’s Home Colour in a paper or card circle with the colours of the spectrum Using string or a pencil spin your disc around…

Rainbow In the laboratory we used a prism to split the wavelengths of light to produce the colours How do rainbows form in the natural world, when there are no prisms?! Rainbows form because of water molecules which act like miniature prisms (to see a rainbow the water droplets must be between you and the light)