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 Form 4 Physics electromagnetic induction topical questions and answers

(a) Figure 15, shows two coils A and B placed close to each other. A is connected to a steady D.C supply and a switch, B is connected to a
sensitive galvanometer.
(i) The switch is now closed. State the observations made on the galvanometer.
(ii) Explain what would be observed if the switch is then open.
(b) The primary coil of a transformer has 1000 turns and secondary coil has 200 turns. The primary coil is connected to a 240V a.c mains supply.
(i) Explain how an e.m.f. is induced in the secondary coil.
(ii) Determine the secondary voltage.
(iii) Determine the efficiency of the transformer given that the current in the primary coil is 0.20A and in the secondary coil is 0.80A.

 (6m 4s)
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