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CAIE A-Level Physics 20.5.4 Electromagnetic Induction Experiments

Practise explaining induction experiments, identifying changing flux and induced-emf direction, and interpreting the factors controlling its magnitude.

Syllabus
2028–2030
Course
Physics 9702
Level
A2

Exam points

  • describe experiments showing that changing magnetic flux induces an emf
  • identify the conditions, observations and direction changes in an induction experiment
  • interpret induced emf in terms of changing flux and circuit motion

20.5.4—Experiments that demonstrate: • that a changing magnetic flux can induce an question 1

[Maximum number: 5]

A capacitor of capacitance 470μ F470 \mu \mathrm{~F} is connected to a battery of electromotive force (e.m.f.) 24 V in the circuit of Fig. 5.1.

Fig. 5.1

Fig. 5.1

The two-way switch S is initially at position X.
P and Q are identical long straight wires, each with a resistance of 5.6kΩ5.6 \mathrm{k} \Omega. These wires are placed near to, and parallel to, each other. Wire Q is connected to a voltmeter.

At time t=0, switch S is moved to position Y so that the capacitor discharges through wire P .

Question (a)

(a)

Explain why there is an induced e.m.f. across wire Q during the discharge of the capacitor.

[ 3 ]

Question (b)

(b)

On Fig. 5.3, sketch a line to suggest the variation with t of the voltmeter reading V.

Fig. 5.3

Fig. 5.3

[ 2 ]
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