Page 231 - Primary Five Science

Overhead Power Lines and Telephone Wires

Overhead telephone and electricity wires installed on poles

expand during hot weather and contract in cold weather. The

wires between two poles are given a certain amount of sag so

that they may contract in on cold days without snapping.

Large Bends in Pipes

The pipes through which hot or cold liquid or gas flows are of-

ten given bends so that they may expand or contract without

cracking.