question

(a) when a convex lens of focal length 30 cm is in contact with a concave lens of focal length 20 cm, find out if the system is converging or diverging.

(b) obtain the expression for the angle of incidence of a ray of light which is incident on the face of a prism of refracting angle a so that it suffers total internal reflection at the other face. (given the refractive index of the glass of the prism is .)

 

 

 

 

 

 

423