Ncert Exercises & Solutions

Electrical energy is transmitted over large distances at high alternating voltages. Which of the following statements is (are) correct?

a.	For a given power level, there is a lower current.
b.	Lower current implies less power loss.
c.	Transmission lines can be made thinner.
d.	It is easy to reduce the voltage at the receiving end using step-down transformers.

1. (a, b, c)
2. (a, b, d)
3. (b, c, d)
4. (c, d)

(2) Hint: The current in the wire depends on the voltage.

Step 1: We have to transmit energy (power) over large distances at high alternating voltages, so the current flowing through the wires will be low because, for a given power (P);

P = E_{rms} I_{rms}, I_{rms} is low when E_{rms} is high .

Power loss = {I^{2}}_{rms} R = low (∵ I_{rms} is low)

Step 2: Now at the receiving end, the high voltage is reduced by using step-down transformers.

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