Introduction

When do we use light?

We use light when we are:

• looking at the stars
• watching a film or video
• seeing microscopic animals
• using a torch in the dark
• looking at a rainbow
• seeing three-dimensional (3D) pictures
• putting on make-up.

Add to this list by thinking of other ways that you use light.

There are many optical gadgets we buy and use, such as the camera, telescope, make-up mirror, spectacles and binoculars. Some are used for fun, but many are an essential part of our lives.

Optical gadgets 'Optical' means related to light and seeing. 'Optical gadgets' are things that use light in some way. Many optical gadgets help us to see or see differently.

Optical technologies

Some pieces of equipment (optical technologies) are commonly used in the many optical gadgets around us today. These include:

light sources such as globes and TV screens
photographic film on which pictures are developed
apertures or small holes through which light can pass
optical fibres, which are thin glass threads through which light can travel
mirrors of various shapes
lenses and prisms of various shapes.

Examine each gadget and ask yourself: 'What is it used for?' Then make a list of which pieces of optical equipment (optical technologies) you can see in the gadget.

For example in a 35 mm camera you may be able to see a lens, a flat mirror, an aperture, photographic film and possibly a light source. You could rule up a table such as the one shown to record your notes. You might indicate (perhaps with a tick) the types of technology you see in the gadget. You can record your answers in the columns across the table.