Question

To improve the resolving power of a compound microscope we should

• A. decrease the diameter of the objective lens.
• B. decrease the focal length of the eye-piece.
• C. increase the refractive index of the medium between the object and objective lens.
• D. increase the wavelength of light.

Hint:

Resolving power of a microscope is 2 mu sin(theta) over 1.22 lambda.

Answer 1

The Correct Option is C

Step 1: Approach
Think of what limits detail: wavelength and the light-gathering cone.

Step 2: Reasoning
A smaller $\lambda$ and a larger numerical aperture $\mu\sin\theta$ give finer resolution. Oil immersion raises $\mu$ and so improves resolution. The eyepiece magnifies the image the objective has already formed, so it cannot add detail.

Step 3: Answer
Option (C).

Final Answer:
The resolving power is proportional to the refractive index of the medium at the objective, option (C). \[ \boxed{\text{Increase the refractive index of the medium}} \]