OP33 understand that light is a form of energy and that it can be converted to other forms


Pythagoras (c.582 BC–c.497 BC), who proposed that light consists of tiny particles which are sent out by the object being viewed to the eyes of the viewer. An alternative theory, attributed to the Greek mathematician Euclid (325 BC–?), is that the eyes send out rays which strike objects and give the sensation of sight. Euclid also studied mirrors and discovered the laws of reflection.


The sun produces a vast amount of energy as about 6 × 108 tonnes of hydrogen are converted every second. The earth, because of its size and distance from the sun, receives about 0.000 000 05% of this energy as heat and light.

Crookes radiometer,

That he invented in 1873

Watch it convert light into kinetic

Light energy comes from the sun, when the light hits the earth it gives the energy to the earth by heating it up.

Light energy gives out heat energy when it strike a dark body! .

This is the energy conversion that takes place in Solar water heating.


is when plants make their own food with light

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Solar Energy

Solar Heating (light energy heat energy)

Make your own Solar Heating contraption

There are other solar cells known as photovoltaic cells, these convert light into electricity. They are very common you will find them on bicycle computers, calculators, road signs ...... you probably used one in the section on energy conversions

and back again