Final answer:
The transformer does not change the frequency of AC voltage; it only changes the voltage level while the frequency remains unaffected.
Step-by-step explanation:
The transformer does not affect the frequency of the AC voltage driving the circuit. The job of a transformer is to change the voltage level, but the frequency of the input AC voltage remains the same at the output. This is because a transformer operates on the principle of electromagnetic induction, where the rate of change in magnetic flux linkage due to the AC in the primary coil induces a voltage in the secondary coil.
If you are looking at other related aspects, when the period of a wave increases, its frequency decreases, and the induced emf in a generator's coil increases if the frequency of rotation is increased. However, these are separate concepts and should not be confused with the operation of transformers where frequency remains unchanged.