Question

The unit of e.m.f is

• A. Joule
• B. Joule-coulomb
• C. Volt-coulomb
• D. Joule/coulomb

Answer 1

The correct option is D

Joule/coulomb

The explanation for correct answer:-

In the case of option D,

1. EMF is produced as the energy is converted from one form to another in a generator or a battery as the device does work on the electric charge being transformed within it.
2. The work done on a unit of electric charge gained per unit of electric charge, $E=\frac{W}{Q}$
3. Here, W is work done which has the unit joule (J) and Q is the charge with the unit coulomb.
4. So, the SI unit of emf is derived as joules per coulomb.

The explanation for incorrect answer:-

In the case of option A,

1. Joule is the SI unit of Work.
2. Hence it is incorrect.

In the case of option B,

1. Joule-Coulomb does not exist.
2. Hence it is incorrect.

In the case of option C,

1. Joule can be written as Volt-coulomb.
2. So Volt-coulomb is also a unit of Work.
3. Hence it is incorrect.

Hence, option D is the correct option.