Once light has been produced, it will keep travelling in a straight line until it hits something else. You can see this with shadows, where light cannot pass by the solid object. Another easy experiment is to shine a torch through a comb and see the straight lines of light on the desk.

Here are some examples of light travelling straight:

The light from the Sun travels in straight lines to the Earth. From the image above you can see that it hits the Earth nearest to the Equator first - This is why it is hotter around the Equator.

Spectrum of Light

You might think that light is bright white. But it actually contains a range of colours.

These can be made visible by refracting light through a prism or glass. This is similar to the effect caused by a rainbow in the sky.