What is the principle of a transformer?

The principle of a transformer is based on the transfer of electrical energy through electromagnetic induction. A transformer operates by utilizing alternating current (AC) flowing through the primary winding, which creates a magnetic field. This magnetic field then induces a voltage in the secondary winding through a process known as electromagnetic induction. This transfer allows electrical energy to be transformed from one voltage level to another without changing the frequency.

The first choice, which mentions generating electrical energy, is not applicable because transformers do not create energy; they simply transfer it from one circuit to another. The second option refers to storing energy in capacitors, which is a different function unrelated to the operation of transformers. The last choice about converting DC to AC is also incorrect since transformers work exclusively with AC. They cannot operate with direct current (DC) due to the nature of electromagnetic induction requiring a changing magnetic field, which is absent in DC. Therefore, the correct answer emphasizes the fundamental operation of transformers in transferring electrical energy via electromagnetic induction.