(A) : Torque on the coil is always maximum, when coil is suspended in a radial magnetic field.
(R) : Torque depends upon the magnitude of the applied magnetic field.

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 question, we need to analyze both the assertion (A) and the reason (R) provided.

### Step 1: Understand the Assertion (A)
The assertion states that "Torque on the coil is always maximum when the coil is suspended in a radial magnetic field."

- A coil suspended in a radial magnetic field means that the magnetic field lines are directed radially outward from a central point.
- When the coil is oriented such that its plane is perpendicular to the magnetic field lines, the torque acting on it will be maximized.

### Step 2: Analyze the Torque Formula
The torque (τ) on a current-carrying coil in a magnetic field is given by the formula:
\[ \tau = n \cdot B \cdot I \cdot A \cdot \sin(\theta) \]
where:
- \( n \) = number of turns in the coil,
- \( B \) = magnetic field strength,
- \( I \) = current flowing through the coil,
- \( A \) = area of the coil,
- \( \theta \) = angle between the magnetic field and the normal to the coil's surface.

### Step 3: Determine the Conditions for Maximum Torque
- For maximum torque, \( \sin(\theta) \) should be equal to 1, which occurs when \( \theta = 90^\circ \).
- In a radial magnetic field, if the coil is oriented such that its area vector is perpendicular to the magnetic field, the torque will indeed be at its maximum.

### Step 4: Understand the Reason (R)
The reason states that "Torque depends upon the magnitude of the applied magnetic field."

- This statement is true; torque is directly proportional to the magnetic field strength \( B \).
- However, the reason does not explain why the torque is maximum when the coil is in a radial magnetic field.

### Step 5: Conclusion
- Both the assertion (A) and the reason (R) are true statements.
- However, the reason does not correctly explain the assertion. Therefore, the correct conclusion is that the assertion is true, but the reason is not a correct explanation for the assertion.

### Final Answer
The assertion (A) is true, and the reason (R) is true, but it is not a correct explanation for (A).