A transformer has 500 primary turns and 10 secondary turns. (a) We have to find the open circuit secondary voltage if the primary voltage is 120 V (rms). (b) Assuming that the secondary is now connected to a resistive load of , we have to find the currents in the primary and secondary windings.

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The transformer equation is

Where is the number of turns in the secondary, and is the number of turns in the primary.

Therefore,

When a resistive load of is connected to the secondary, the current in the secondary coil of the transformer will be

The current in the primary coil of the transformer can be found by equating the power dissipated in the secondary and the power supplied to the primary coil of the transformer. That is