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प्रश्न
Point out two differences between e.m.f. and potential difference as applied to electric circuits.
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उत्तर
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.
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संबंधित प्रश्न
Name a device that helps to maintain a potential difference across a conductor.
State two causes of energy loss in a transformer.
The values of current (I) flowing through a given resistor of resistance (R), for the corresponding values of potential difference (V) across the resistor are as given below:
| V (volts) | 0.5 | 1.0 | 1.5 | 2.0 | 2.5 | 3.0 | 4.0 | 5.0 |
| I (amperes) | 0.1 | 0.2 | 0.3 | 0.4 | 0.5 | 0.6 | 0.8 | 1.0 |
Plot a graph between current (I) and potential difference (V) and determine the resistance (R) of the resistor.
You have three resistors of values 2Ω, 3Ω and 5Ω. How will you join them so that the total resistance is more than 7Ω?
1) Draw a diagram for the arrangement
2) Calculate the equivalent resistance.
What do the letters p.d. stand for?
State the relation between potential difference, work done and charge moved.
How much energy is transferred by a 12 V Power supply to each coulomb of charge which it moves around a circuit?
Calculate the power used in the 2 Ω resistor in each of the following circuits: a 4 V battery in parallel with 12 Ω and 2 Ω resistors.
Explain the analogy between the flow of charge (or current) in a conductor under a potential difference with the free fall of a body under gravity.
Calculate the potential difference between the two terminals of a battery if 100 joules of work is required to transfer 20 coulombs of charge from one terminal of the battery to the other.
