AC Transformer

The ratio of the secondary to primary voltages in a transformer equals the ratio of the number of loops in their coils, i.e. .
Assuming that resistance is negligible, the electrical power output of a transformer equals its input.  Hence, . Rearranging, we have Also,

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A travel adapter has a step-up transformer, the 120 V input of which is transformed to a 240 V output. The primary coil has 18 loops and draws a current of 0.200 A when in use. What is the number of loops in the secondary coil?

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What is the current output of the secondary coil?

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