Fig. 1 shows a bimetallic strip used in a simple thermostat. Name the property of the two materials that causes the strip to bend when it is heated.

Assessment: Design & Technology: Product Design 9252 | Paper 1 Mock 01 | Technical, designing and making principles Subject: Design & Technology: Product Design - 9252

Question 1 Report

9252-p1-materials-bimetallic-strip-1

Fig. 1 shows a bimetallic strip used in a simple thermostat. Name the property of the two materials that causes the strip to bend when it is heated.

Answer Details

The two materials have different rates of thermal expansion [1], also called different coefficients of expansion. When heated, one layer lengthens more than the other. Because the layers are bonded together, the strip bends rather than both layers expanding freely.

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