What is mutual inductance in transformers?

Mutual inductance refers to the phenomenon where a change in current flowing through one coil induces a voltage in a nearby coil due to the magnetic field generated by the first coil. This principle is fundamental to the operation of transformers, where two coils, known as the primary and secondary, are situated close enough that the magnetic field produced by the current in the primary coil affects the secondary coil. When an alternating current flows through the primary coil, it creates a changing magnetic field that surrounds the coil. This changing field links with the secondary coil, thereby inducing a voltage across it according to Faraday’s law of electromagnetic induction.

In the context of transformers, mutual inductance is crucial because it allows for the transfer of electrical energy from one coil to the next without a direct electrical connection. It enables transformers to step up or step down voltages in AC circuits efficiently.

The other choices pertain to different concepts. The first option refers to electrical resistance rather than the inductive interaction between coils. The third option describes a process distinct from mutual inductance, as it relates to the conversion of energy forms rather than the interaction of magnetic fields. Finally, the fourth option discusses a measurement of energy loss, which is not relevant to the definition of mutual inductance itself.