Question

A.C power is transmitted from a power house at a high voltage as

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

Answer 1

Answer: (B)

it is more economical due to less power loss

Power wasted as heat is $\frac{V^2}{R}$ and $I^{2}R$.

In long distance transmission of electricity, long wires are used which have very high resistance, $R\propto l$, so direct multiplication of $R$ into a high number will increase power wasted. So current should be low, voltage can be high because resistance is denominator, so it will reduce the power wasted as heat. So less power is wasted therefore it is more economical way.