Difference Between Galvanometer and Ammeter

Galvanometer vs Ammeter
 

Ammeter and galvanometer are two devices that are used in the field of electronic and electrical measurements. Galvanometer is a very important device that is used to develop other measuring devices. It is also used to measure electrical currents. Ammeter is also a device that is used to measure electrical current. A working understanding in these devices is required in fields such as electronic engineering, electrical engineering, magnetism and various other fields. In this article, we are going to discuss what are galvanometer and ammeter, the working principles of galvanometer and ammeter, the similarities and finally the difference between galvanometer and ammeter.

Ammeter

An ammeter is a device that is used to measure the current going through the device. Ammeter has two terminals to connect external wires. These terminals are generally polarized. A mechanical ammeter consists of a conducting coil placed inside an external magnetic field. The coil is supported by a spiral spring, which applies a torque on an axis that is on the surface of the coil and normal to the external magnetic field. When current passes through the coil, the coil tends to rotate due to the magnetic moment created by the external magnetic field on the magnet created by the coil. This torque is proportional to the current passing through the coil for a given system. The amount of torque actually depends on the external magnetic field, the number of turns of the coil, the effective surface area of the coil and the current passing through it. The spring returns the coil to the original position when the current is stopped.

Apart from this model there are several other models of ammeters. Digital ammeters use an operational amplifier modified as an ammeter along with an analog to digital conversion (ADC) circuit.

Galvanometer

A galvanometer is a type of mechanical ammeter. A galvanometer takes the name from Luigi Galvani, an Italian physicist who greatly contributed to the field of electrical power. He was also a famous physician who invented bioelectricity.

There are several types of galvanometers. These are tangent galvanometers, astatic galvanometers, mirror galvanometers and ballistic galvanometers. A galvanometer can be modified to form a volt meter. This is done by using a high valued resistor in series with the galvanometer.

A galvanometer can either be a center zero galvanometer or a corner zero galvanometer (normal galvanometer). A center zero galvanometer is capable of measuring currents going both ways as the center of the scale is zero. Other galvanometers are capable of measuring current only in one direction.