Electromotive Force and Internal Resistance

Electromotive force (e.m.f)

The energy per unit charge converted from the other forms of energy into electrical energy to move the charge across the whole circuit

E.m.f formula

Unit for e.m.f

Volt (V)

In circuit, cell is the device....

......that supplies e.m.f

Internal Resistance

Resistance against the moving charge in the source

Load Resistance

The effective resistance against the moving charge outside the source of electric

Terminal Potential Difference

Potential difference across the two terminals of an electric source

The relationship between e.m.f. and the terminal potential difference

E=IR+Ir

In open circuit ( when the switch is off).....

.....the voltmeter shows the reading of the e.m.f

In close circuit ( when the switch is on)....

.....the voltmeter shows the reading of the potential difference across the cell