Question

9. Answer the following questions. (20) a. There is a charge moving back and forth between two points. Sketch the electric field lines generated by the charge. (10) b. People believe that the high voltage AC (alternating current) power transmission lines generate low frequency electromagnetic waves harmful to human health. In some countries, high voltage DC (direct current) power transmission is partly being implemented. Could it be a solution to the health hazard of EM waves? Why? (10)

plz....help me..

Answer 1

a. It will be simply sinusoidal in nature. Since an oscillating charge produces EM waves.

b. There exists a number of reasons why DC is preferred as compared to AC specifically for long distance power lines. Major two reasons are

1. AC cables suffer from skin effect in which the total circuit current tends to concentrate near the surface of the cable with a very little traveling in the center of the wire.

2. AC cables must transmit reactive power, which is not useful power for transmission purposes. DC cables have need not transmit a reactive component and can use their entire cross sectional area for active power.

But the conversion equipment is expensive at both ends. So it is only used on long distances.