Question

Two cables of copper are of equal lengths. One of them has a single wire of area of cross-section A, while other has 10 wires of cross-sectional area $\frac{A}{10}$ each. Give their suitability for transporting A.C. and D.C.

• A. only multiple strands for A.C., either for D.C.
• B. only multiple strands for A.C., only single strand for D.C.
• C. only single strand for D.C., either for A.C.
• D. only single strand for A.C., either for D.C.

Answer 1

Answer: (A)

only multiple strands for A.C., either for D.C.

Answer 2

The major portion of the A.C. flows on the surface of the wire. So where a thick wire is required, a number of thin wires are joined together to give an equivalent effect of a thick wire.
Therefore multiple strands are suitable for transporting A.C. Similarly multiple strands can also be used for D.C.
Therefore, the correct option is (A) : only multiple strands for A.C., either for D.C.