Correct option is A
· Eddy current damping occurs when a conductor moves in a magnetic field, which induces an electromotive force (emf) in the conductor. If a closed path is provided, an eddy current flows. This current produces an electromagnetic torque that opposes the direction of motion, providing the necessary damping force.
· Damping torque is used to reduce oscillations and bring the pointer to rest within a short time. It should be proportional to the velocity of the moving current but independent of the operating current.
· Eddy current damping is often used in Permanent Magnetic Moving Coil (PMMC) instruments, which are used to measure voltage or current. PMMC instruments have many advantages, including high accuracy, low power consumption, and a high torque to weight ratio.
