Question

Unit of e.m.f of a cell is
A. dyne
B. volt
C. ampere
D. joule

Answer 1

Hint: The full form of e.m.f is electromotive force. It is the potential difference that the cell produces across its terminals. This potential difference causes a flow of electrons in the circuit when the cell is connected across a conductor.

Complete step-by-step answer:
Cell is a device that produces potential differences between its terminals. The terminals of the cell are called anode (negative terminal) and cathode (positive terminal).
A collection of cells is called a battery.
When a potential difference is created around a charged particle, a work is done and on the particle and thus the particle comes into motion.
When a cell or battery is connected across a conductor, the battery produces a potential difference across the conductor. Since a conductor has free electrons, due to this potential difference the electrons begin to flow through the circuit.
The potential difference across a battery is called e.m.f of the battery. The full form of e.m.f is electromotive force. Electromotive force is the energy provided by the battery to one coulomb of charge.
The unit of potential is volt. Since electromotive force (e.m.f) is a potential difference (change in potential across a length), it has the unit potential i.e. volts.
Therefore, the unit of e.m.f is volt.
Hence, the correct option is B. volt.

Note: Kindly note that a cell or a battery is a source of energy and not a source of charge. A cell produces a potential difference, which is equal to the energy given to one coulomb of charge. When we connected the terminals of the cell across a conductor, due to the potential difference there is flow of electrons through the conductor and the cell.
A cell produces flow of electrons in the circuit but it does not produce any charge.