Efficiency in Electric Motors Steps:

• Efficiency is the ratio of useful output power to input power, expressed as a percentage.
• Formula: Output power = (efficiency × input power) / 100.
• Input power = 1 kW, efficiency = 53%.
• Output power = (53 × 1) / 100 = 0.53 kW.

Why A is correct:

• Directly applies the efficiency formula: output = input × (efficiency/100).

Why the others are wrong:

• B: Assumes 90% efficiency, not 53%.
• C: Approximates input divided by efficiency (1/0.53 ≈ 1.89 kW), which is total power needed for 1 kW output.
• D: Unrelated; far exceeds input power, violating energy conservation.

Final answer: A