Final answer:
Transformers operate on the principle of electromagnetic induction, based on Faraday's law which involves inducing an electric current by changing magnetic flux in a conductor loop.
Step-by-step explanation:
The principle by which transformers operate is through electromagnetic induction. Transformers are essential devices in distributing electric power efficiently and safely over long distances. They function based on Faraday's law of induction, which indicates that a changing magnetic flux within an area enclosed by a conducting loop induces an electric current in that loop. This is observed with the two coils present in a transformer: the primary and secondary coils.
When alternating current (AC) flows through the primary coil of a transformer, it creates a time-varying magnetic field. The presence of an iron core further traps and augments this magnetic field. As a result, this changing magnetic field induces a magnetic flux through the secondary coil, which, according to Lenz's law, will generate an induced AC voltage in the secondary coil.
Transformers are utilized for either stepping up or stepping down voltage levels to suit various applications, like transmitting electricity over long distances or supplying power to households. It's pertinent to note that transformers only work with AC and not direct current (DC) because they rely on the fluctuating magnetic field created by alternating current to operate effectively.