A step-down transformer reduces 2200 V to 110 V. The primary draws 5 A of current and secondary supplies 80 A. The percentage efficiency of the transformer will be:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 80
The efficiency of a transformer is the ratio of the output power (secondary) to the input power (primary).
\( \displaystyle \eta = \frac{V_s I_s}{V_p I_p}\times100\% \)
\( \displaystyle \eta = \frac{(110\,\mathrm{V})(80\,\mathrm{A})}{(2200\,\mathrm{V})(5\,\mathrm{A})}\times100\% \)
\( \displaystyle \eta = \frac{8800\,\mathrm{W}}{11000\,\mathrm{W}}\times100\% \)
\( \displaystyle \eta = 80\% \)