Ammeter, Voltmeter and Galvanometer

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Ammeter, voltmeter and galvanometer

Current measuring Instruments

The magnitude of current flowing through a metallic conductor varies from very large values of hundred of amperes required to start electric motors to very small values of current in

milliamperes A or microamperes  A and computer circuit current in nanoamperes A or pico amperes A 

Galvanometer
Electric current can be detected with a Galvanometer. This instrument can detect smaller amount of current up to thousand of times smaller than what a micro-ammeter can measure or detect.

Circuit symbol ( See figure 3 above)

Galvanometer is majorly used where cuÅ•rent detection are of paramount .  It is very useful in meter bridge and potentiometer experiments.
For the centre -zero galvanometer,  the pointer is at the center zero mark when no current flows through it.
When current  passes through the galvanometer, the pointer deflects to the right or the left depending on the  direction of the current

Ammeter

Ammeter is used to measure the exact amount of current in a circuit. Ammeter is used to measure large current and a milliammeter  or a microammeter is used to measure smaller currents.

Ammeters are generally represented in a circuit as shown in the diagram above.(fig 1)

Most ammeters are designed to measure both Direct and Alternating current.

Ammeter are always connected in series to the load or resistor to measure current passing through the load or the resistor.

Voltmeter.

Voltmeter is an instrument to measure potential difference in volts(V) or millivolts (mV).

Voltmeters are always connected in parallel across the load or resistor to measure the p.d in volts across the load or the resistor

see fig 2 above for circuit symbol of voltmeter.

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