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Heat Questions - GCSE Level

Q11. The diagram shows an electric kettle being used to heat some water.

(a) Complete the following sentences to describe how the water in the kettle is warmed by convection.

When the kettle is switched on, the temperature of the water near the heating element increases. As the temperature of the water increases, the water expands and becomes less dense . The heated water rises towards the top of the kettle. The movement of the water sets up a convection current .

[4 marks]

(b) Three different designs of hot water bottle are each filled with water at 90 °C from the kettle.

The diagram shows the three different designs.

Each hot water bottle is made from a different material but holds the same amount of water.

State two factors that would affect the time it would take the hot water bottles to cool down to room temperature.

Any two from:

surface area

room temperature

(surface) colour

thickness of material

how good an insulator the material it is made of is

[2 marks]

(6 marks total)