Assertion (A): Transformer is useful for stepping up or stepping down voltages.
Reason (R): Transformer is a device used in D.C. circuits. In the context of the above two statements, which one of the following is correct?

Correct Option

Assertion (A) states that a transformer is useful for stepping up or stepping down voltages. This statement is correct. A transformer is an electrical device designed to change the voltage level of an alternating current (AC) supply. It operates on the principle of mutual induction, allowing it to either increase (step up) or decrease (step down) the voltage.

Reason (R) states that a transformer is a device used in D.C. circuits. This statement is incorrect. Transformers require a continuously changing magnetic flux to induce an electromotive force (EMF) in the secondary coil. Alternating current (AC) provides this changing magnetic field. Direct current (DC) produces a constant magnetic field, which does not induce a voltage in the secondary coil, rendering the transformer ineffective in DC circuits.

Therefore, Assertion (A) is true, but Reason (R) is false, making option (c) the correct answer.

Incorrect Options

Options (a), (b), and (d) are incorrect because they contradict the factual analysis of the statements. Reason (R) is false, as transformers do not operate with direct current. Assertion (A) is true, as transformers are indeed used for stepping up or stepping down voltages.