Question

State the principle on which a step-up transformer works.

Answer 1

When the terminals of the primary coil are connected to the source of alternating e.m.f., a varying current flows through it, which also produces a varying magnetic field in the core of the transformer. Thus, the magnetic field lines linked with the secondary coil vary and induce an e.m.f. in the secondary coil. The induced e.m.f. varies in the same manner as the applied e.m.f. in the primary coil varies, and thus, has the same frequency as that of the applied e.m.f.