(A) : In case of M.C.G the torque on the coil is maximum in any position of the coil
(R) : In case of M.C.G the concave shaped magnetic poles render the field to be radial between them so that the plane of the coil is always parallel to the lines of induction even after deflection

Options

A. Both 'A' and 'R' are true and 'R' is the correct explanation of 'A'.
B. Both 'A' and 'R' are true and 'R' is not the correct explanation of 'A'
C. 'A' is true and 'R' is false
D. 'A' is false and 'R' is false

Answer

To solve the given question, we need to analyze both the assertion (A) and the reason (R) provided in the context of a moving coil galvanometer (MCG).

### Step-by-Step Solution:

1. **Understanding the Assertion (A)**:
- The assertion states that in the case of a moving coil galvanometer, the torque on the coil is maximum in any position of the coil.
- In a moving coil galvanometer, the coil experiences torque due to the interaction of the magnetic field with the current flowing through the coil.

2. **Torque Calculation**:
- The torque (τ) on a coil in a magnetic field is given by the formula:
\[ τ = n \cdot i \cdot A \cdot B \cdot \sin(θ) \]
where:
- \( n \) = number of turns in the coil
- \( i \) = current flowing through the coil
- \( A \) = area of the coil
- \( B \) = magnetic field strength
- \( θ \) = angle between the magnetic field and the normal to the plane of the coil.

3. **Maximum Torque Condition**:
- The torque is maximum when \( \sin(θ) \) is maximum, which occurs at \( θ = 90° \) (i.e., when the plane of the coil is perpendicular to the magnetic field).
- However, the assertion claims that the torque is maximum in any position, which is not true. The torque is not maximum at all positions; it varies with the angle \( θ \).

4. **Conclusion on Assertion**:
- Therefore, the assertion (A) is **false**.

5. **Understanding the Reason (R)**:
- The reason states that the concave-shaped magnetic poles render the field to be radial between them, ensuring that the plane of the coil is always parallel to the lines of induction even after deflection.
- In a moving coil galvanometer, the concave-shaped poles do create a radial magnetic field, which means that the magnetic field lines are directed radially inward or outward from the poles.

6. **Conclusion on Reason**:
- The reason (R) is **true** because the radial magnetic field does help maintain the alignment of the coil with the magnetic field lines, but it does not imply that the torque is maximum at all positions.

7. **Final Evaluation**:
- Since the assertion is false and the reason is true, we conclude that both statements cannot be correct simultaneously.

### Final Answer:
- Assertion (A) is **false**.
- Reason (R) is **true**.