Question

Transformers are used

• A. in DC circuit only
• B. in AC circuits only
• C. in both DC and AC circuits
• D. neither in DC nor in AC circuits

Answer 1

Answer: (B)

in AC circuits only

Transformers work on the principle of voltage induction by the linkage of changing magnetic flux between between the two cores. Changing magnetic flux requires changing/alternating current.
Transformers are used only in AC circuits. In DC circuits, no alternating/changing magnetic flux is produced to induce voltage in secondary from the primary terminals of the transformers.