The discussion focuses on the operational mechanics of a moving-coil galvanometer, specifically how it indicates current strength. When the current is applied, the pointer moves to a position proportional to the current, such as 8mA. Upon the sudden withdrawal of current, the pointer initially remains at its last reading due to inertia, but eventually returns to zero as the coil spring stretches and then retracts to its equilibrium position, aided by a damping mechanism to control the return speed.
PREREQUISITESElectronics engineers, physics students, and anyone interested in the principles of measurement in electrical circuits will benefit from this discussion.
A coil spring. The angle is proportional to the torque on the spring, which is proportional to the current in the coil.phyphysics said:I know that the pointer of the galvanometer makes use of the turning effect to indicate the strength of the current. Say, the pointer is moved to the position of 8mA, if the current is suddenly withdrawn, the pointer would be pointing back to zero. What's the mechanism behind this?
But as the needle turns the spring stretches. When the current drops to 0 the spring just returns to its equlibrium position (there is probably some kind of damper to slow the return).phyphysics said:When the current is just switched off, then there is no turning effect on both the hairsprings and the iron cylinder. By inertia, the pointer must still pointing at the original reading, say, 8mA, so how can the pointer be flicked back to zero when the current suddenly drops to 0 ?