Question

A microscope will have maximum resolving power if, to illuminate the specimen, it uses light of

• A. red colour.
• B. green colour.
• C. yellow colour.
• D. blue colour.

Hint:

Smaller wavelength always gives better resolution in optical instruments.

Answer 1

The Correct Option is D

Step 1: Resolving power of a microscope.
Resolving power is inversely proportional to the wavelength of light used:
\[ \text{Resolving power} \propto \frac{1}{\lambda} \]
Step 2: Compare wavelengths of colours.
Among visible colours, blue light has the shortest wavelength.

Step 3: Effect on resolving power.
Shorter wavelength results in smaller diffraction limit and better resolution.

Step 4: Conclusion.
Therefore, a microscope has maximum resolving power when blue light is used.