Question

In a step-down transformer, the number of turns in the secondary coil is 20 and the number of turns in the primary coil is 100. If the voltage applied to the primary coil is 120 V, then what is the voltage output from the secondary coil?

(a) 24 V

(b) 12 V

(c) 6 V

(d) 18 V

The question was asked in final exam.

My query is from Alternating Current in portion Alternating Current of Physics – Class 12

Answer 1

The correct choice is (a) 24 V

For explanation: Given: Ns = 20; Np = 100; Vp = 120 V

For a step-down transformer ➔ \(\frac {N_s}{N_p} = \frac {V_s}{V_p}\)

Vs=\(\frac {N_s \times V_P}{N_p}\)

Vs=\(\frac {20 \times 120}{100}\)

Vs=24 V

Therefore, the voltage output from the secondary coil is 24 V.