Question

Two isosceles prism of prism angle `A` and refractive index `mu` are placed with their bases touching each other. This system can act as a crude converging lens. The focal length of the lens for `A=10^(@),mu=1.5` and a ray of light incident on a prims at a height of `1` cm from its base, is approximately.
A. `11.5` cm
B. `23.0`cm
C. zero
D. `5.75`cm

Answer 1

Correct Answer - A
For small angles `tan delta=h/f`

Also `tan delta=delta=(mu-1)A`
`h/((mu-1)A)=f`
`10^(0)=(pi)/18` radian
`f=(1xx18)/(0.5xx3.14)=11.5cm`