Voltage

Description

The electric potential difference between two points is called voltage. The voltage is equal to the work done per unit charge to move a test charge between two points against static electric field.

Electric potential is given by
electric potential energy per unit charge, measured in joules per coulomb. Electric potential is a per-unit-charge quantity. The zero of electric potential can be chosen at any point.

The negatively charged particles are always attracted by high voltage, whereas positively charged particles are pulled towards lower voltages. Hence the conventional current always flows from higher voltage to lower voltage through a conductor. To flow a current from lower voltage to higher voltage, an energy source is need to push it against the opposing electric field.

Units of Voltage

The voltage is indicated by symbol V and is also unit for emf (electromotive force) and potential difference. The volt is named after the Italian physicist Alessandro Volta, who invented the first battery.

Measurement of Voltage

Voltage is measured with the help of Instruments called voltmeters, and potentiometers. Voltmeter is an indicating instrument and the voltage is measured by measuring current passing through a parallel resistor. The potentiometer is a null type instrument and the voltage is measured by balancing the bridge.