Question Detail
Question
In a moving coil galvanometer, pole faces of U-shaped magnet are made concave
Correct Answer
Option D is the correct answer.
Detailed Explanation
The concave shape of the pole faces in a moving coil galvanometer serves two main purposes:1. To make the field radial: This ensures that the plane of the coil is always parallel to the magnetic field lines, irrespective of the coil's angular position. This maximizes the torque (τ = NIAB sinθ, where sinθ is always 1) and makes the deflection proportional to the current.2. To increase the field strength: The concave shape helps to concentrate the magnetic field lines, thereby increasing the strength of the magnetic field in the region where the coil moves.
Hint
Consider how the shape of the poles affects both the direction and density of magnetic field lines.