R: How does a Moving-Coil Galvanometer Indicate Current Strength?

In summary: The pointer is attached to a coil of wire that is suspended between two magnets. When a current flows through the coil, it creates a magnetic field that interacts with the magnetic field of the magnets, causing the coil to rotate and move the pointer. In summary, the pointer of the galvanometer makes use of the turning effect to indicate the strength of the current. When the current is suddenly withdrawn, the pointer returns to zero due to the coil spring mechanism and the interaction between the magnetic fields of the coil and the magnets. The spring stretches as the needle turns, and when the current drops to zero, the spring returns to its equilibrium position.
  • #1
phyphysics
25
0
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 Say, the pointer is moved to the position of 8mA, if the current is suddenly withdrawn, the pointer would be pointing back to zero.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?
 
Physics news on Phys.org
  • #2
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 Say, the pointer is moved to the position of 8mA, if the current is suddenly withdrawn, the pointer would be pointing back to zero.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?
A coil spring. The angle is proportional to the torque on the spring, which is proportional to the current in the coil.

AM
 
  • #3
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 ?
 
  • #4
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 ?
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).

AM
 

What is a moving-coil galvanometer?

A moving-coil galvanometer is a scientific instrument used to detect and measure small electric currents. It consists of a coil of wire suspended in a magnetic field, which is deflected when a current passes through it.

How does a moving-coil galvanometer work?

The coil in a moving-coil galvanometer is connected to a pointer that moves along a scale to indicate the strength and direction of the current. The magnetic field created by the current interacts with the magnetic field of the galvanometer, causing the coil to rotate.

What are the main components of a moving-coil galvanometer?

The main components of a moving-coil galvanometer are the coil, the pointer, the magnetic field, and a spring to provide a restoring force. The galvanometer may also include a mirror and a light source for more precise measurements.

What is the difference between a moving-coil galvanometer and a moving-magnet galvanometer?

The main difference between a moving-coil galvanometer and a moving-magnet galvanometer is the type of coil used. In a moving-coil galvanometer, the coil moves while the magnet remains stationary. In a moving-magnet galvanometer, the magnet moves while the coil remains stationary.

What are the practical applications of a moving-coil galvanometer?

Moving-coil galvanometers are commonly used in scientific experiments and in various industries to measure small electric currents. They are also used in the design and testing of electronic circuits and for monitoring electrical equipment for faults or malfunctions.

Similar threads

Replies
13
Views
2K
  • Introductory Physics Homework Help
Replies
5
Views
2K
  • Introductory Physics Homework Help
Replies
6
Views
4K
Replies
49
Views
3K
  • Introductory Physics Homework Help
Replies
17
Views
1K
  • Introductory Physics Homework Help
Replies
2
Views
851
  • Introductory Physics Homework Help
Replies
12
Views
294
  • Electromagnetism
2
Replies
42
Views
722
  • Introductory Physics Homework Help
Replies
8
Views
2K
  • Introductory Physics Homework Help
Replies
1
Views
2K
Back
Top