gcsescience.com                                       29                                       gcsescience.com


What is the Ray Diagram for a Concave Lens?

A concave lens is a diverging lens which
makes the rays of light disperse and spread further apart.
It does the opposite of a convex lens.

Concave Lens showing a Ray Diagram with Divergent Light Rays

The bottom of the object is placed on the principle axis.
Two rays of light are drawn from the top of the object.

The first ray of light is parallel to the principle axis
and bends away from it on the right hand side of the lens.
To find the correct angle for this ray of light you
trace it back through the focal point F on the left side.
This part of the ray is virtual and is drawn with a
dotted line because the light never really goes there.

The second ray of light goes from the top of the object
and passes through the centre of the lens. The second
ray of light does not change direction (see ray diagrams).

You draw the top of the image where the two rays of light cross.
The bottom of the image is still on the principle axis.

You can see that the image is not the same as the object.
The image is called virtual because the light rays
really cross there (compare this with a real image).
The image is called upright because it is the right way up
(compare this with an inverted image). The image is smaller
than the object and on the same side of the lens as the object.

back      Links      Waves      Light      Revision Questions      next

gcsescience.com       Physics Quiz       Index       Lens Quiz       gcsescience.com

Home      GCSE Chemistry      GCSE Physics

Copyright © 2015 gcsescience.com. All Rights Reserved.