Question

Explain the meaning of the term e.m.f. of the cell.

Answer 1

E.m.f. is an abbreviation that is used for the electromotive force. It is denoted by $\varepsilon$. It is considered to be the terminal potential difference (voltage) of a source when no current is drawn by the circuit. In other words, it can be understood as the maximum voltage a source can have without any loss.

Complete step-by-step answer:
E.m.f. is calculated in the t batteries or stored energy sources. When a conductor is placed in a variable flux linkage a small amount of e.m.f. is induced in the conductor. The induced e.m.f. is equivalent to the rate of change of flux linkage of the conductor.
$\varepsilon =-\dfrac{d\phi }{dt}$
The minus sign represents that the induced e.m.f is in the opposite direction to the force inducing it. I was postulated by Heinrich Friedrich Emil Lens. And is popularly known as Lens law.
According to Lenz’s law, in electromagnetics the current flowing in a conductor due to induced e.m.f flows in a direction such that it opposes the change that induces that e.m.f. This was postulated in the year 1864.
e.m.f is considered to be the work done by the electromagnetic field over a conductor per unit charge. As work done is a scalar quantity the e.m.f is also considered to be a scalar quantity.

Note: The e.m.f of a battery can be calculated with the help of a device named potentiometer. A potentiometer is a kind of variable resistor only it is also used to provide a controlled voltage supply to a circuit. It is necessary to find the e.m.f of the batteries to know the maximum efficiency of the battery.