A transformer with turns ratio \( \displaystyle\frac{N_1}{N_2}=\frac{100}{1} \) is connected to a 240 V ac supply. If the primary and secondary resistance are 1.0 kΩ and 1 Ω respectively, then find the output power?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 5.76 W
For an ideal transformer the voltages are in the same ratio as the turns, \( V_2/V_1 = N_2/N_1 \). The 240 V acts across the primary, and the 1 Ω resistance is the one connected across the secondary, so the output power is the power delivered to it.
\( \displaystyle V_2 = V_1\,\frac{N_2}{N_1} = 240\,\mathrm{V}\times\frac{1}{100} = 2.4\,\mathrm{V} \)
\( \displaystyle I_2 = \frac{V_2}{R_2} = \frac{2.4\,\mathrm{V}}{1\,\Omega} = 2.4\,\mathrm{A} \)
\( P_{\mathrm{out}} = V_2I_2 = 2.4\,\mathrm{V}\times2.4\,\mathrm{A} = 5.76\,\mathrm{W} \)