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 Form 4 Physics electromagnetic induction topical questions and answers

(a) One of the causes of energy loss in a transformer is heating in the coils when current flows. State:
(i) The reason why the current causes heating.
(ii) How the heating can be minimized.
(b) The input voltage of a transformer is 240V and its output is 12v. When an 80W bulb is connected across the secondary coil, the current in the primary coil is 0.36A.
Determine:
(i) The ratio #N_p/N_s# of the transformer , (where Np is the number of turns in the primary coil and Ns is the number of turns in secondary coil)
(ii) The power input of the transformer.
(iii) The power output of the transformer.
(iv) The efficiency of the transformer.

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