Reflections are usually caused by shiny things, such
as MIRRORS, that show a reversed image of whatever is placed in
front of them. The image seems to be as far behind the mirror as the object is
in front of it. Not only mirrors make reflections, however. Most objects
reflect some of the light that falls on them. In daytime we see familiar
objects like grass, trees, and the sky only because they reflect light from the
Sun into our eyes.
A rough surface, such as this rippling pond, causes light rays to
bounce off it in many different directions. It may still be possible to make
out an image on the surface, or, if it is very rough, the image is very broken
up. Most objects reflect light in this irregular way. Although we can see them,
we cannot see any images reflected in their surfaces.
A mirror is a very smooth, highly polished piece of metal
or plastic that reflects virtually all the light that falls onto it. The
reflection appears to be behind the mirror and may look bigger, smaller, or the
same size as the thing it is reflecting, depending on the mirror’s
shape. We use mirrors when checking our appearance or driving. They also play
an important part in telescopes, microscopes, cameras, and other optical
(light-based) instruments.
A concave mirror curves or bends inwards and makes an object look
bigger and nearer than it actually is. It works by making light rays seem to
come from a point in front of the mirror, which is closer to our eyes. Concave
mirrors are important in such things as bicycle reflectors and reflecting
telescopes.
Drivers use mirrors to see traffic coming up behind them. It is
important for drivers to see as much of the road behind as they can, so wing
mirrors and rear-view mirrors are convex. A drawback is that they make vehicles
on the road behind look smaller and further away than they would in a flat
mirror of the same size. Drivers must remember that the vehicles are nearer
than they appear.
