The resolving power of a compound microscope will increase with

Options

A. Red light is used to illuminate the object
B. Violet light is used to illuminate the object instead of red light
C. Infra red light is used to illuminate the object instead of visible light
D. The microscope is in normal adjustment

Answer

To solve the question regarding the conditions under which the resolving power of a compound microscope increases, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Resolving Power**:
- Resolving power is the ability of a microscope to distinguish between two closely spaced points. It is a crucial factor in determining the clarity and detail of the image produced by the microscope.

2. **Write Down the Formula for Resolving Power**:
- The formula for resolving power (R) of a microscope is given by:
\[ R = \frac{n \sin \theta}{0.61 \lambda} \]
- Here, \( n \) is the refractive index of the medium, \( \theta \) is the half-angle of the maximum cone of light that can enter the lens, and \( \lambda \) is the wavelength of light used.

3. **Analyze the Formula**:
- From the formula, we can see that resolving power is directly proportional to the numerical aperture (\( n \sin \theta \)) and inversely proportional to the wavelength (\( \lambda \)).
- This means that increasing the numerical aperture or decreasing the wavelength will increase the resolving power.

4. **Determine How to Increase Resolving Power**:
- To increase the resolving power, we can either:
- Increase the numerical aperture by using lenses with better light-gathering capabilities.
- Decrease the wavelength of the light used (for example, using violet light instead of red light).

5. **Select the Correct Option**:
- The question asks how the resolving power of a compound microscope will increase. Based on our analysis, we conclude that decreasing the wavelength will lead to an increase in resolving power.
- Therefore, the correct answer is that the resolving power will increase with a decrease in wavelength.

### Final Answer:
The resolving power of a compound microscope will increase with a decrease in wavelength.