Phyisics Primary Power Supply

Question

An ideal transformer has 50 turns in its primary and 400 turns in its secondary. 14-VV ac is connected to the primary. What is the power supplied to the primary? Not sure how to do this problem.

Answer 1

The basis of transformers is that essentially V_pI_p = V_sI_s so power is the same and transformers are nearly 100% efficient. By induction V_p/V_s = N_p/N_s so here the voltage steps up by a factor of 8. Because the power is constant the current will be reduced by a factor of 1/8.

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