Question

A diverging beam of light from a point source S having divergence angle $\alpha$, falls symmetrically on a glass slab as shown. The angles of incidence of the two extreme rays are equal. If the thickness of the glass slab is $t$ and the refractive index $n$, then the divergence angle of the emergent beam is:

• A. zero
• B. $\alpha$
• C. ${\sin }^{-1}$(1/n)
• D. $2{\sin }^{-1}$(1/n)

Answer 1

The correct option is B $\alpha$

Since rays after passing through the glass slab just suffer lateral displacement hence we have angle between the emergent rays as αα.