In a transformer, what happens when current runs through one coil?

In a transformer, when current runs through one coil, it generates a magnetic field due to the flow of electricity. This magnetic field induces a voltage in the other coil, which is known as mutual inductance. The fundamental principle of a transformer relies on this induction, allowing the voltage in the secondary coil to be either increased or decreased based on the turns ratio of the coils.

The phenomenon occurs because the current in the primary coil creates a changing magnetic field that envelops the secondary coil, inducing a current if the secondary coil is part of a closed circuit. The induced current in the secondary coil is an effect of the initial current running through the first coil, hence the term "replicated," though not necessarily equal in magnitude.

As for the other options, they do not encapsulate the primary function of a transformer. The first option suggests a direct increase in voltage in the same coil, which does not happen; a transformer's key role is to transfer energy between coils, not to amplify the voltage of a single coil independently. The second option regarding voltage drop across the coil typically relates more to resistance and load than the induction principle at play in a transformer. The last option about generating heat refers to resistive losses rather than the operational principle of induct