Which of the following statements is correct regarding transformers? a. if any current is present in the primary coil, a current will be induced in the secondary coil. b. the fewer loops present in the primary coil, the more current induced in the secondary coil. c. if an alternating current is present in the primary coil, a current will be induced in the secondary coil. d. a secondary loop with a small cross-sectional area will induce a greater current than a loop with a large cross-sectional area and the same number of loops.

C. If an alternating current is present in the primary coil, a current will be induced in the secondary coil.

Explanation:

As we know by the principle of induction given by faraday there will be induced EMF in the coil if the magnetic flux linked with the coil will change with time.

now we know that when alternating current passes through the primary coil then it will change the flux linked with the secondary coil.

Due to change in the flux of secondary coil it will induce the EMF in that coil.

so here correct answer will be

C. If an alternating current is present in the primary coil, a current will be induced in the secondary coil.

t = 1/400 h   ⇔ 0.0025 h ⇔ 9s ⇔ 0.15 m

any of the answers are correct.