When wavelength of light used in optical instruments $\mathrm{A}$ and $\mathrm{B}$ are $4500 Å$ and $6000 Å$…
When wavelength of light used in optical instruments $\mathrm{A}$ and $\mathrm{B}$ are $4500 Å$ and $6000 Å$ respectively, the ratio of resolving power of $A$ to $B$ will be
16:9
7:1
9:16
4:3
Solution
Resolving power of an optical instrument $\propto \frac{1}{\lambda}$
$\frac{\text { Resolving power at } \lambda_{1}}{\text { Resolving power at } \lambda_{2}}=\frac{\lambda_{1}}{\lambda_{2}}$
$\left[\right.$ Limit of resolution $\left.\propto \frac{1}{\text { resolving power }}\right]$
$\therefore$ Ratio of resolving power $=\frac{6500}{4500}=\frac{4}{3}=4: 3$