Question

when does expansion and contraction of the metal occur​

Answer 1

Answer:

What extra heat energy is given to the metal from any source than expansion takes place.

When the normal temperature decreases than metal will contract and contraction takes place.

for e. g. During summer the irons of platform expand and in rainy and wintry days they contract.

Answer 2

In welding science, expansion and contraction of metals is of greatest importance. When a solid metal is heated, its atoms vibrate more about their position in the lattice (a network of crossed bars). This causes them to take up more space, so the solid metal expands from its original shape. Most substances expand when heated and contract when cooled—as then the atoms settle back into their normal state of vibratioN

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