Out of the following, which statement is incorrect ?

1. The lamination of core prevents loss of energy due to eddy currents.
2. The core is made of soft iron.
3. A transformer can be used with d.c.
4. A closed core is used so as to provide a closed path for magnetic field lines.

A transformer can be used with d.c.

Reason — Transformers are used with a.c. circuits to step up or step down voltage. In d.c. circuits, since the current is constant, induction cannot happen. Therefore, transformers are not used with d.c. circuits.