106 Aptitude Test Problems in Physics
Determine the distance Ax between the
points at which these rays intersect the op-
tical axis after being reflected at the mir-
ror.
4.20. The inner surface of a cone coated by a
reflecting layer forms a conical mirror. A
thin incandescent filament is stretched in
the cone along its axis.
Determine the minimum angle a of the
cone for which the rays emitted by the fila-
ment will be reflected from the conical sur-
face not more than once.