Find focal length of the system shown in figure from left hand side.

Answer

A, C

Explanation

`mu_1=2,mu_2=1.5, R_1=+40 and R_2=oo`
Using the equation
`1/f=(mu_2/mu_1-1)(1/R_1-1/R_2)`, we have
`1/f=(1.5/2-1)(1/(+40)-1/oo) rArr f=-160cm`

Therefore, from left hand side it behaves like a concave lens of focal length `160cm`