A moving coil galvanometer consists of a coil of N turns are area A suspended by a thin phosphor bronze strip in radial magnetic field B. The moment of inertia of the coil about the axis of rotation is l and c is the torsional constant of the phosphor bronze strip. When a current i is passed through the coil, it deffects through an angle `theta`
Magnitude of the torque experienced by the coil is independent of

Options

A. a.N
B. b.B
C. c.i
D. d.l

Answer

To solve the problem, we need to determine the factors on which the torque experienced by a moving coil galvanometer depends. The torque (τ) experienced by the coil can be expressed in terms of the magnetic field (B), the current (I), the number of turns (N), and the area (A) of the coil.

### Step-by-Step Solution:

1. **Understanding Torque in a Magnetic Field**:
The torque (τ) experienced by a coil in a magnetic field is given by the formula:
\[ \tau = N \cdot B \cdot I \cdot A \]
where:
- \(N\) = number of turns in the coil
- \(B\) = magnetic field strength
- \(I\) = current passing through the coil
- \(A\) = area of the coil

2. **Identifying Dependencies**:
From the formula, we can see that the torque τ is directly proportional to:
- The number of turns \(N\)
- The magnetic field strength \(B\)
- The current \(I\)
- The area \(A\)

3. **Identifying Independence**:
The only variable that does not appear in the torque equation is the moment of inertia \(l\) of the coil. The moment of inertia is related to the rotational dynamics of the coil but does not directly affect the torque experienced by the coil in the magnetic field.

4. **Conclusion**:
Therefore, the magnitude of the torque experienced by the coil is independent of the moment of inertia \(l\).

### Final Answer:
The magnitude of the torque experienced by the coil is independent of the moment of inertia \(l\).