Calculate the resolving power of a telescope when light of wavelength `540 nm` is used. Diameter of objective lens is `6 cm`.

Options

A. `9.1 xx10^(-4)"rad"^(-1)`
B. `0.1xx10^(-4)"rad"^(-1)`
C. `5xx10^(-4)"rad"^(-1)`
D. `6xx10^(-4)"rad"^(-1)`

Answer

B

Explanation

Given `D=6cm=6xx10^(-2)m`
`lambda=540nm=540xx10^(-9)m`
Resolving power of the telescope
`RP=(D)/(1.22lambda)=(6xx10^(-2))/(1.22xx540xx10^(-9))`
`=(6)/(122xx54)xx10^(8)` rad
In terms of `"rad"^(-1)`
`RP^(-1)=(1)/(RP)=(122xx54)/(6xx10^(8))"rad"^(-1)`
`=0.1 xx 10^(-4)"rad"^(-1)`