Question

A step down transformer reduces 220 V to 110 V. The primary draws 5 ampere of current and secondary

supplies9 ampere. The efficiency of transformer is -

• A. 20%
• B. 44%
• C. 90%
• D. 100%

Answer 1

Answer: (C)

90%

Answer 2

% efficiency = $\frac{P_{out}}{P_{in}}$× 100 = $\frac{110 \times 9}{220 \times 5}$× 100

= 90%