The focal length of a converting lens are `f_(v) and f_(r)` for violet and red lights, respectively. Which of the following is correct?

Options

A. `f_(v)ltF_(r)`
B. `f_(v)=F_(r)`
C. `f_(v)gtF_(r)`
D. It depends on the average refractive index

Answer

A

Explanation

Let wavelengthgs of red and violet lights are `lambda_(r) and lambda,` resepectively
As we know that
`lamda_(r) gt lambda_(v)Rightarrow mu_(v) gt mu_(r) (therefore mualpha (1)/(lambda))`
`Rightarrow f_(r) gt f_(v) (therefore mualpha (1)/(lambda))`