Electromotive Force

The electromotive force of a cell is the work done by a source in driving a unit charge around a complete circuit.

S.I Unit: joules per coulomb (JC^{-1}) or volts (V)

Formula:

electromotive \space force = \frac{work done}{charge}

• Electromotive force is not a force. It is a scalar quantity and exists whether current flows or not

• Other forms of energy is being converted to electrical energy

Series

• Cells connected in series increase overall e.m.f.

Parallel

• Cells connected in parallel does not increase overall e.m.f

• Advantages:
  • Cells will last longer before going 'flat'
  • Cells are able to supply a higher current