A radio set operates at `6 V DC`. A transformer with 18 turns in the secondary coil is used to step down the input `220 V AC emf to 6 V AC emf`. This `AC emf` is then rectified by another circuit to give `6 V DC` which is fed to the radio. Find the number of turns in the primary.

Explanation

We have,
`|(epsilon_2)/(epsilon_1)| = N_2/N_1` epsilon or, `N_1 = |(epsilon_1)/(epsilon_2)| N_2 = 220/6 xx 18 = 660`