A point source (A) is kept on the axis of a hemi- spherical paperweight made of glass of refractive index`mu = ( 3 )/( 2)` . The distance of the point source from the centre (O) of the sphere is R where R is radius of the hemisphere. Use paraxial approximations for answering following questions (a) Find the change in radius of curvature of the wave- fronts just after they enter the glass at O. (b) Find the radius of curvature of the wavefronts at point P just outside the glass.

Answer

(a)`(R)/(2)` (b)10R