The number of turns in the primary coil when the transformer is used to step down the AC emf from 220V to 6V , assuming that it has 18 turns in its secondary coil is
Answer & explanation
Correct answer: option 3
$\frac{V_s}{V_p} = \frac{N_s}{N_p} $
$\Rightarrow N_p = \frac{V_p}{V_s} N_s = \frac{220}{6} \times 18 = 660$