Certain galvanometers have a fixed core made of non magnetic metallic material. The function of this metallic material is
- (A)to oscillate the coil in magnetic field for longer period of time
- (B)to bring the coil to rest quickly✓ Correct
- (C)to produce large deflecting torque on the coil
- (D)to make the magnetic field radial
Answer: (B)
Solution
As the coil swings in the magnetic field, the changing flux through the non-magnetic metallic core induces eddy currents in it. By Lenz's law these induced currents oppose the motion that creates them, so they act as an electromagnetic brake on the coil. This damping removes the unwanted swinging of the pointer about its final position and gives a steady reading. Hence the metallic core serves to bring the coil to rest quickly.
JEE Main · 2023 · 08 Apr 2023 · Shift 1 · Single correct option