Question

A transformer is used to light a 100 Wand 110 V lamp from a 220 V mains. If the main current is 0.5 A. The

efficiency of the transformer is approximately-

• A. 30%
• B. 50%
• C. 90%
• D. 10%

Answer 1

Answer: (C)

90%

Answer 2

% h = $\frac{P_{out}}{P_{in}}$× 100 = $\frac{100}{220 \times 0.5}$× 100 = 90%