Physics 9702 · AS & A Level · Characteristics of alternating currents

Characteristics of alternating currents — practice question

(a)[2]

The average value of an alternating current is zero. Explain why a resistor still heats up when an alternating current flows through it.

(b(i))[2]

Electrical energy is often sent using alternating high voltages. Suggest why high voltages are chosen.

(b(ii))[2]

Electrical energy is often sent using alternating high voltages. Suggest why the voltage alternates.

Worked solution & mark scheme

This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “heating is proportional to $I^2R$; $I^2$ is always positive” …

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