Question

What is difference between e.m.f. and terminal voltage

Answer 1

Electromotive Force (emf) is the energy (work) given by an electric cell to flow a unit charge in the whole circuit (containing cell).

Terminal Voltage is the work done by an electric cell to flow a unit charge between two points of a circuit.

So, difference between EMF and Terminal Voltage is that EMF is measured for whole circuit whereas Terminal Voltage is measured for two points of a circuit.


We can say that all the Terminal Voltages of a cell form a EMF.

Thus, E = V1 + V2 + V3 + V4 +..........+ Vn.

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Hope it was helpful.

Answer 2

Answer:

Relationship between e.m.f and terminal voltage of cell

Let W be work done in moving a test charge q outside and inside the cell.

W1 is the work done in moving the test charge q outside the cell ....here w is the work done in moving the test charge q inside the electrolyte of the cell.

The law of conservation of energy,

W=W1+w

Dividing the above eq:-

$\frac{w}{q} \frac{w1}{q} + \frac{w }{q}$

By both the eq.....we get:-

$\frac{w}{q} = e \\ \frac{w1}{q } = v \\ \frac{w}{q} = v$

Therefore,

$v = e - v$

Hence,when current is drawn from a cell the terminal voltage V is less than its e.m.f. e by n amount r

equal to the voltage drop v inside he cell.

When a heavy current is drawn from he cell,a large number of charge carries low through the electrolyte so more work is done.

This result in more voltage V.The terminal voltage V of cell also depends on the amount of current I drawn from it.