Electrical power
3 marks · NormalExplain why appliances such as kettles and toasters have elements made of materials with high resistance, while the connecting wires in a circuit have low resistance.
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Heating elements have high resistance so that when current flows, significant heat is produced and transferred. Connecting wires are made to have low resistance to avoid them heating up, which would waste energy and could be dangerous.
Must show: High resistance causes heating: for appliances designed to heat, Low resistance in wires: prevents unwanted heating, Mention of efficiency or safety
Common mistakes: Saying all wires should have high resistance
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Marking points
M1 · 1 mark · States that high resistance in elements is to produce heat.
M2 · 1 mark · States connecting wires have low resistance to avoid heating.
B1 · 1 mark · Refers to safety/efficiency as a reason for low resistance in connecting wires.
Worked solution
Appliances like kettles and toasters need to get hot, so their elements are made with high resistance to convert electrical energy into heat. The connecting wires should have as little resistance as possible so they don’t get hot, making the circuit safe and efficient.