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Question
Point out two differences between e.m.f. and potential difference as applied to electric circuits.
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Solution
Electromotive force or e.m.f. of a cell is potential difference between its two electrodes when it is in open circuit, i.e., not sending current in the external circuit; while potential difference is the difference in potential between the terminals when the cell is in closed circuit or it is sending current in the given circuits, e.m.f. is always greater than potential difference or terminal voltage of a cell on account of energy being spent in driving charge through the circuit.
RELATED QUESTIONS
A battery of emf 12 V and internal resistance 2 Ω is connected with two resistors A and B of resistance 4 Ω and 6 Ω respectively joined in series.
Find:
1) Current in the circuit
2) The terminal voltage of the cell
3) The potential difference across 6Ω Resistor
4) Electrical energy spent per minute in the 4Ω resistor.
What is the SI unit of potential difference?
The values of potential difference V applies across a resistor and the corresponding values of current I flowing in the resistor are given below:
| Potential differences, V (in volts) | : | 2.5 | 5.0 | 10.0 | 15.0 | 20.0 | 25.0 |
| Current, I (in amperes) | : | 0.1 | 0.2 | 0.4 | 0.6 | 0.8 | 1.0 |
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Write proper word from the following group of words in the blank.
(magnetism, 4.5V, 3.0V, gravitational attraction, potential difference, potential, higher, lower, 0V)
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Exercise.
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