Figure, shows a concavo-convex lens `mu_(2)`. What is the condition on the refractive indiecs so the at the lens is diverging?

Options

A. `2mu_(3) lt mu_(1)+mu_(2)`
B. `2mu_(3) gt mu_(1)+mu_(2)`
C. `mu_(3) gt 2(mu_(1)-mu_(2))`
D. None of these

Answer

b.

Explanation

`(mu_(2))/(V)-(mu_(1))/(-u_(0))=(mu_(2)-mu_(1))/(-2R)`
`(mu_(3))/(V_(f))-(mu_(2))/(V)=(mu_(3)-mu_(2))/(-R)`
`(mu_(3))/(V_(f))+(mu_(1))/(u_(0))=(mu_(1)-mu_(2))/(2R)+(mu_(2)-mu_(3))/(R)`
`:. (mu_(1)-mu_(2))/(2) lt mu_(3)-mu_(2) rArr mu_(1)-mu_(2) gt 2mu_(3)-2mu_(2) rArr mu_(1)+mu_(2) lt 2mu_(3)`