Consider a hollow sphere of radius R, in which a light source is placed at its centre. A square plate of side length S is held in place within the sphere by a pole of length L units. The square plate's position is then such that the displacement between the centre of the square and the light source is R-L units.

The square plate is also oriented in a way such that an imaginary line drawn perpendicular to the surface of the plate and passing through the plate's centre will pass through the light source.

Determine the surface area of the shadow formed on the spherical shell, due to the square plate.

quick question.  Is the surface of the sphere reflective?  This will help in determining if I have to consider light reflecting off of the sphere and thus getting around the plate to the surface underneath.  Also can we consider the pole to have 0 thickness and thus not play a part in the shadow casting?

Posted by Daniel on 2009-08-19 11:53:35