Question

Suppose a british official tried transmitting electricity generated from London to New Delhi in ${17}^{th}$ century when India had no access to electricity. Taking the distance between London & New Delhi approximately as $7000km$, find out the time taken to transmit electricity (assume a metal conductor for transmission).

• A. $0.1s$
• B. $0.023s$
• C. $2.3s$
• D. Electricity can not be transmitted for such long distances

Answer 1

The correct option is B $0.023s$

We know that in a material, electricity travels at a speed of light, $c=3\times {10}^{8}m/s$ .

We also know that, $Speed=\frac{Distance}{Time}$

$⟹Time=\frac{Distance}{Speed}$

Distance (in metre) = $7\times {10}^{6}m$

∴ Time = $\frac{7000000}{300000000}s$

Hence, time taken for transmission of electricity from London to New Delhi will be $0.023s$.