JEE Physics 2023 Question with Solution

Given: A compound microscope is to be used for better analysis by improving its resolving power.

Find: Which change increases the resolving power.

The resolving power $P$ of a microscope is given by

$$P = \frac{2 \mu \sin \theta}{1.22 \lambda}$$

where $\mu$ is the refractive index of the medium and $\lambda$ is the wavelength of light.

To improve resolving power:

• Increasing $\mu$ increases $P$.
• Decreasing $\lambda$ increases $P$.

So, the useful change among the given options is to increase the refractive index of the medium between the object and the objective lens.

The solution states option A, but the working supports B. Therefore, based on the solution working, the most defensible correct option is B.