Question

AC power is transmitted from a powerhouse at a high voltage as

• A. Power cannot be transmitted at low voltage
• B. The rate of transmission is faster at high voltages
• C. A precaution against theft of transmission lines
• D. It is more economical due to less power loss

Answer 1

The correct option is D

It is more economical due to less power loss

Explanation for the correct option

D: It is more economical due to less power loss

1. Due to the heating effect of the current, there occurs a loss of power in transmission lines.
2. Loss in power transmission ($P_l$) due to the current ($I$) flowing in the transmission line of resistance ($R$) is given by, $P_l=I^{2}R$ …………(a)
3. The relation connecting the power ($P$), current, and voltage ($V$) is given by, $I=\frac{P}{V}$ ……………….(b)
4. Using equation (b) in equation (a), we get, $P_l=\frac{P^2}{V^2}\times R$
5. Clearly, loss in power transmission is inversely proportional to the voltage.
6. On increasing the voltage, the power losses are reduced and vice versa.
7. Hence, the power is transmitted from a powerhouse at a high voltage to reduce the power loss and consequently make the transmission economical.

Hence, option (D) is correct.