In the year 1884, Friedrich Dexler invented Ammeter whereas the deflection of a magnetic compass needle by the current in a wire was first described by Hans Oersted in 1820 only.
What is an Ammeter?
In the year 1884, Friedrich Dexler invented Ammeter which is a measuring instrument useful in electrical devices. It is also called an ampere meter because an ampere is the SI unit of current. An Ampere meter i.e., an ammeter can also take precise measurements of current, even in small units of milli-amperes or micro-amperes. For measuring the exact value of current, Ammeter is placed in the way of a series connection with the circuit because in the series the whole current of the circuit will pass through it.
What is Galvanometer?
At the University of Halle in Germany, the earliest form of the electromagnetic galvanometer was devised in 1820 by Johann Schweigger and the deflection of a magnetic compass needle by the current in a wire was first described by Hans Oersted in 1820 only. This device is more applicable for the measurement of current if the direction if we want to know the flow of current also. It uses a moving coil, and this coil is free to rotate between the permanent magnets. With the flow of current through the coil, deflection can be seen in the coil of the galvanometer. This deflection of the coil is directly proportional to the magnitude of the flowing current. The galvanometer is a versatile device i.e., we can convert it into an ammeter by connecting the resistance in its parallel. Not only this, but we can also convert it into a voltmeter, when the resistance is connected in series with it, in the circuit.
Difference between Ammeter and Galvanometer
The galvanometer is the mechanical device used for determining the magnitude along with the direction of the current, whereas the ammeter is the electric device used for measuring only the magnitude of the current.
The magnetic field is required for the working of the galvanometer whereas it is not necessary for the ammeter. (A magnetic field is a vector field that describes the magnetic influence on moving electric currents and charges, and magnetic materials.)
The accuracy of the galvanometer is less as compared to the ammeter because it measures both magnitude and direction.
The sensitivity of the galvanometer is more than that of the ammeter and the galvanometer is mostly used in bridges and the potentiometer for knowing the zero current whereas the ammeter is directly connected in series with the circuit whose magnitude is to be measured. The galvanometer is made sensitive so that the needle of the galvanometer shows a large deflection even when a small amount of voltage or current is supplied across the coils.
The galvanometer is only used for measuring the direct current, whereas the ammeter is used for measuring both the direct and alternating current i.e., both DC and AC.
A galvanometer has more resistance than an ammeter since the ammeter has a shunt parallel to the coil of the galvanometer.
Conversion of Galvanometer in Ammeter
A galvanometer is converted into an ammeter by connecting it in parallel with shunt resistance i.e., low resistance. Depending on the range of the ammeter, suitable shunt resistance is chosen.
In the circuit given above
RG – Resistance of the galvanometer
G- Galvanometer coil
IG – Total current passing through the galvanometer which corresponds to full-scale reading
Rs – Value of shunt resistance
I – Total current passing through the circuit
When current IG passes through the galvanometer, the current through the shunt resistance is given by IS = I – IG, and the voltages across the galvanometer and shunt resistance are equal due to the parallel nature of their connection.
Therefore RG*IG= (I- IG)*Rs
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In the year 1884, Friedrich Dexler invented Ammeter which is a measuring instrument useful in electrical devices. The galvanometer is the mechanical device used for determining the magnitude along with the direction of the current. The galvanometer is the mechanical device used for determining the magnitude as well as the direction of the current, whereas the ammeter is the electric device used for measuring only the magnitude of the current. The magnetic field is required for the working of the galvanometer whereas it is not necessary for the ammeter. (A magnetic field is a vector field that describes the magnetic influence on moving electric currents and charges, and magnetic materials). The galvanometer is only used for measuring the direct current, whereas the ammeter is used for measuring both the direct and alternating current i.e., both DC and AC. The galvanometer is made sensitive so that the needle of the galvanometer shows a large deflection even when a small amount of voltage or current is supplied across the coils. Yes, we can also convert it into a voltmeter, when the resistance is connected in series with it, in the circuit. Difference between Ammeter and Galvanometer FAQs
Who invented the Ammeter?
What is a Galvanometer?
State any three differences between the Galvanometer and Ammeter.
Why a galvanometer is made sensitive?
Can a galvanometer be converted into Voltmeter?
