The current sensitivity of a moving coil galvanometer can be increased by

Options

A. Increasing the magnetic field of the permeanent magnet
B. Increasing the area of the deflecting coil
C. Increasing the number of turns in the coil
D. All of these

Answer

To solve the question regarding how to increase the current sensitivity of a moving coil galvanometer, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Current Sensitivity**:
- Current sensitivity (S) of a moving coil galvanometer is defined as the deflection produced per unit current flowing through the coil. It can be expressed mathematically as:
\[ S = \frac{N \cdot A \cdot B}{k} \]
where:
- \(N\) = Number of turns in the coil
- \(A\) = Area of the deflecting coil
- \(B\) = Magnetic field strength
- \(k\) = Torsional constant of the coil

2. **Identifying Factors Affecting Current Sensitivity**:
- From the formula, we can see that current sensitivity is directly proportional to \(N\), \(A\), and \(B\). This means if any of these quantities increase, the current sensitivity will also increase.

3. **Analyzing Each Option**:
- **Increasing the Magnetic Field (B)**:
- If we increase the strength of the magnetic field in which the coil is placed, it will increase the current sensitivity.
- **Increasing the Area of the Deflecting Coil (A)**:
- Increasing the area of the coil will also lead to an increase in current sensitivity as it is directly proportional to the area.
- **Increasing the Number of Turns in the Coil (N)**:
- Increasing the number of turns in the coil will likewise increase the current sensitivity.

4. **Conclusion**:
- Since all three options (increasing \(B\), \(A\), and \(N\)) lead to an increase in current sensitivity, the correct answer to the question is:
- **All of these**.

### Final Answer:
The current sensitivity of a moving coil galvanometer can be increased by increasing the magnetic field of the permanent magnet, increasing the area of the deflecting coil, and increasing the number of turns in the coil. Therefore, the correct answer is **all of these**.