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EXPANSION AND CONTRACTION

By Siti Mazenah Dienta Rochani binti Mohamed Tajudin and Alissa

Syafika binti Che Rodzna1D/Jauzi

PBS Form 1 Band 6 - Heat

PBS Form 1 Band 6 - Heat 2

Mercury in Glass Thermometer

A mercury in glass thermometer works on the expansion and contraction of mercury in the bulb of the thermometer.

When the thermometer is used to measure the temperature of a hot object, the mercury in the bulb expands and forces the mercury in the glass tube to go up.

When the thermometer is used to measure the temperature of a cold object, the mercury in the bulb contracts and the mercury in the glass tube goes down.

PBS Form 1 Band 6 - Heat 3

Bimetallic Strip in Fire Alarm

A bimetallic strip is made of two different metal strip, such us copper and iron.

Copper expands faster than iron when heated.

The forces that arise due to an equal expansion of the two metals cause the bimetallic strip to bend.

Bimetallic strips are used as automatic switches in fire alarms and as thermostats in electrical appliances such as iron, air-conditioners, rice cookers and refrigerators to keep the temperature in these appliances constant.

PBS Form 1 Band 6 - Heat 4

Gaps In Railway Tracks and Roads

Gaps are left in between sections of rails to allow for the expansion of the rails during very hot weather.

Concrete roads are built with expansion gaps to allow for the expansion of the concrete during hot weather.

PBS Form 1 Band 6 - Heat

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Rollers in Concrete and Steel Bridges

Concrete bridges and steel bridges have rollers on one end to allow for expansion on hot days and cold days.

PBS Form 1 Band 6 - Heat 6

~THE END~Hope you enjoy our presentation. Life is what you want it to be!