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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.
संबंधित प्रश्न
The values of current I flowing in a given resistor for the corresponding values of potential difference V across the resistor are given below:
| I (amperes) | 0.5 | 1.0 | 2.0 | 3.0 | 4.0 |
| V (volts) | 1.6 | 3.4 | 6.7 | 10.2 | 13.2 |
Plot a graph between V and I and calculate the resistance of that resistor.
State two causes of energy loss in a transformer.
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?
What is the potential difference between the terminals of a battery if 250 joules of work is required to transfer 20 coulombs of charge from one terminal of battery to the other?
A p.d. of 10 V is needed to make a current of 0.02 A flow through a wire. Wire p.d. is needed to make a current of 250 mA flow through the same wire?
Calculate the current flowing through each of the resistors A and B in the circuit shown in the following figure.
A current of 100 mA. flows through a wire. The charge on an electron is 1.6 × 10-19 C. Find the number of electrons passing per second through the cross-section of the conductor.
100 J of heat is produced each second in a 4 Ω resistor. The potential difference across the resistor will be:
Assertion (A): Charges flow from higher potential to lower potential.
Reason (R): Current flows mainly due to the flow of electrons.
