The primary voltage and primary current of a transformer are 220 V and 10 A. The ratio of the number of turns on the secondary coil to the number of turns on the primary coil is 2:1. The values of voltage and current at the output are
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → \( 440\,\mathrm{V} \) and \( 5\,\mathrm{A} \)
For an ideal transformer the voltages are in the ratio of the turns, and the power is the same in the primary and the secondary.
\( \displaystyle \frac{V_s}{V_p} = \frac{N_s}{N_p} = 2 \;\Rightarrow\; V_s = 2 \times 220\,\mathrm{V} = 440\,\mathrm{V} \)
\( \displaystyle V_p I_p = V_s I_s \;\Rightarrow\; I_s = \frac{220 \times 10}{440} = 5\,\mathrm{A} \)
This is a step-up transformer: the voltage doubles and the current halves.
Note: This question is from NCERT (2026-27). NTA sets numerical questions from NCERT too, so do not ignore NCERT while practising numericals.
NCERT (2026-27):
Transformers – “… That is, if the secondary coil has a greater number of turns than the primary (Ns > Np), the voltage is stepped up (Vs > Vp). This type of arrangement is called a step-up transformer. … For example, if the primary coil of a transformer has 100 turns and the secondary has 200 turns, Ns/Np = 2 and Np/Ns=1/2. Thus, a 220V input at 10A will step-up to 440 V output at 5.0 A.”