- What does a lens do?
- Why do things look bigger or smaller or otherwise distorted when seen through a lens?
Lenses have been around for a very long time. This isn’t too suprising – as soon as humans starting working with glass, it’s not hard to imagine someone looking through a curved piece and noticing that it made things look strange.
The most likely uses for lenses through most of history were to see small things more clearly and to start fires. The latter use is fairly easy to understand: lenses are very good at focussing beams of light. Since we know that light tends to increase temperature, it makes sense that a highly focussed beam of light could be strong enough to start a fire.
But why does focussing rays of light make objects appear magnified?