The discussion revolves around the operation of a moving-coil galvanometer and how it indicates current strength. Participants are exploring the mechanics behind the pointer's movement and its return to zero when current is withdrawn.
The discussion is active, with participants providing insights into the mechanics of the galvanometer. Some have suggested that the spring's behavior is key to understanding the pointer's return to zero, while others are questioning the assumptions about inertia and the effects of current withdrawal.
There is an implicit assumption that the participants have a foundational understanding of the principles of electromagnetism and mechanics relevant to galvanometers. The discussion does not provide complete information about the damping mechanism mentioned.
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 Say, the pointer is moved to the position of 8mA, if the current is suddenly withdrawn, the pointer would be pointing back to zero.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 ?