2022 · Specimen · 9702/04 | Q7

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Available practice: 77 of 100 marks. Parts 1(b), 4(b)(i), 4(c), 6(a)(ii), 6(b)(ii), 7(a)(i), 7(a)(ii), 9(b)(i), 9(c), 10(b)(ii) await marking support. Scores cover available parts only.

A solenoid has a coil C of wire wound tightly about its centre. The coil C has 96 turns. The uniform magnetic flux Φ, in Wb, in the solenoid is given by the expression Φ = 6.8 × 10⁻⁶ × I, where I is the current, in A, in the solenoid.

(b)Calculate the average electromotive force (e.m.f.) induced in coil C when a current of 3.5 A is reversed in the solenoid in a time of 2.4 ms.

Fig. 7.1 — see the question text for what it shows

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Calculate Show your working. The method can earn marks even when the final value is wrong, and a bare answer often cannot.

[2 marks]

A solenoid has a coil C of 96 turns wound tightly about its centre, and the uniform magnetic flux in the solenoid is Φ = 6.8 × 10⁻⁶ × I where I is the solenoid current.

The d.c. supply in Fig. 7.1 is now replaced with a sinusoidal alternating supply.

(c)Describe qualitatively the e.m.f. that is now induced in coil C.

Answer guidance

Describe Say what happens, in order. Reasons are not required unless the question also asks why.

[2 marks]

9702/04/SP/22Cambridge International AS & A Level Physics 9702 · Specimen 2022 · Paper 4 · Question 7