A 1.5 HP motor runs on 230 V and draws 6 A with an efficiency of 85%. What is the electrical input power and approximate mechanical output?

• A. Electrical input = 230 V × 6 A = 1380 W; mechanical output ≈ 1173 W.
• B. Electrical input = 230 V × 6 A = 1380 W; mechanical output ≈ 880 W.
• C. Electrical input = 230 V × 6 A = 1380 W; mechanical output ≈ 1000 W.
• D. Electrical input = 230 V × 6 A = 1380 W; mechanical output ≈ 1500 W.

Answer: (A)

This question tests how input electrical power, efficiency, and mechanical output relate. The electrical input power is simply voltage times current: 230 V × 6 A = 1380 W. The efficiency tells us what fraction of that input becomes useful mechanical work, so the mechanical output is 0.85 × 1380 ≈ 1173 W. That’s about 1.57 horsepower (since 1 HP ≈ 746 W). So the electrical input is 1380 W and the approximate mechanical output is 1173 W. The other options would imply a different efficiency or miscalculate the relationship between input and output.