Contains the full lesson along with a supporting toolkit, including teachers’ notes.
The mysteries of light
Light has always intrigued scientists. Interest really exploded when Newton discovered that visible ‘white’ light is composed of a series of coloured lights. He used a prism to split white light into its constituent colours and another prism to recombine the colours as white light. He published his major work on light called Opticks in 1704. His theory of ‘particles’ was generally accepted until the wave theory of light emerged.
Many famous experimental and theoretical scientists have contributed to the process leading to our current level of understanding of light as a form of electromagnetic radiation. Such scientists include Maxwell, Hertz, Bohr, Michelson and Einstein. We now know that light behaves like straight line rays and also like waves. It also behaves like particles, which we now callphotons.
What is the electromagnetic spectrum?
Light is not the only form of electromagnetic radiation. The total range of electromagnetic radiation is called theelectromagnetic spectrum. The spectrum is usually divided into seven sections. This is shown below along with the constituent colours of visible light.
Radio waves have the longest wavelengths (105 – 10-3 metres) while gamma rays are the shortest (10-11 – 10-14 metres).
The term electromagnetic derives from the fact that the wave is a result of changing electric and magnetic fields. Allelectromagnetic radiations travel in a vacuum at the same speed, generally referred to as the speed of light.