In this article, we will discuss the important differences between an ammeter and a galvanometer. Both an ammeter and galvanometer are the measuring instruments used in electrical and electronic circuits for the measurement of electric current.
The basic difference between the two instruments is that the ammeter can measure only the magnitude of the electric current, while the galvanometer can measure both the magnitude and direction of the current.
What is an Ammeter?
Ammeter is an electronic measuring instrument used to measure the magnitude of electric current flowing through an electrical or electronic circuit. It is also known as the ampere meter. However, an ammeter can only measure the magnitude of electric current, but not the direction. On the upside the ammeter, it is a more accurate instrument for the measurement of electric current. It is always connected in a series of circuits whose current is to be measured. One of the most significant characteristics of the ammeter is that it must ideally have zero internal resistance.
Based on the type of current measured, ammeters are of two types namely, DC ammeter and AC ammeter. Ammeters can also be classified into two types depending upon the construction as electromechanical ammeter and electronic ammeter.
What is a Galvanometer?
A Galvanometer is also a measuring instrument used to measure the electric current flowing through an electric or electronic circuit. It is an electromechanical instrument used to measure the current’s strength and direction in a circuit. A galvanometer typically consists of a permanent magnet, a moving coil, an iron core, a non-magnetic frame, a suspension wire, and a control spring.
Whenever an electric current passes through the moving coil placed between the two poles of the permanent magnet, a force act on it which moves it. A pointer is attached to this movable coil which can deflect on a scale to show the readings. The deflection of the pointer on the scale is directly proportional to the magnitude of the current in the circuit.
However, the galvanometer can only be used to measure direct current only. In the galvanometer, the zero is located at the center of the scale, and the pointer can deflect on both sides. Hence, along with the magnitude, it can also show the direction of the current in the circuit.
Difference between Ammeter and Galvanometer
The key differences between an ammeter and a galvanometer are given in the following table.
| Key | Ammeter | Galvanometer |
| Definition | An ammeter is a measuring device used to measure the magnitude of current in a circuit. | A galvanometer is a measuring device used to measure the current’s magnitude and detect the current’s direction. |
| Type of device | Ammeter can be an electromechanical ammeter or an electronic ammeter. | Galvanometer is always an electromechanical device. |
| Direction of current | Ammeter cannot detect the direction of current in the circuit. | Galvanometer can detect the direction of current in the circuit. |
| Position of zero on the scale | Ammeter has a zero mark on the left of the scale. | Galvanometer has a zero mark on the centre of the scale. |
| The type of current can be measured | Ammeter can be used for measuring alternating current as well as direct current. | Galvanometer is used only to measure direct current. |
| Magnetic flied | Ammeter can work with (as in electromechanical ammeter) or without (electronic ammeter). | Galvanometer requires a magnetic field to work. |
| Converted into voltmeter | Ammeter cannot be converted into a voltmeter. | Galvanometer can be converted into a voltmeter by connecting a resistor of high resistance in series with it. |
| Interchangeability | An ammeter cannot be used in place of a galvanometer. | A galvanometer can be used in place of an ammeter. |
| Accuracy | Ammeter is a highly accurate device for current measurement. | Galvanometer is a less accurate device than an ammeter. |
| Sensitivity | The sensitivity of an ammeter is lesser. | The sensitivity of a galvanometer is more than that of the ammeter. |
| Uses | Ammeter is mostly used in electrical and electronic circuits to measure the strength of the electric current flowing in the circuit. | Galvanometer is used in electronic bridges and potentiometers. |
Conclusion
In conclusion, this is all about the differences between an ammeter and a galvanometer. An ammeter is a current-measuring device used in electrical and electronic circuits to measure the strength of the electric current, while a galvanometer is a current-measuring device that can measure both the magnitude and direction of the current in the circuit. Also, we can convert a galvanometer into an ammeter by connecting a low-resistance wire in parallel and into a voltmeter by connecting a high resistance in series with it.
