A 3 horsepower, 100 V DC motor is 85%...

Question 1 of 27070eUa05HXYf0hC4LKCw2Pa

A 3 horsepower, 100 V DC motor is 85% efficient when developing its rated output. What is the current?

Back

Question 1 of 27070

Q

A 3 horsepower, 100 V DC motor is 85% efficient when developing its rated output. What is the current?

🔍 Key Concepts

• Horsepower to watts conversion (1 HP = 746 watts) to find the motor’s mechanical output power in watts • Efficiency = output power ÷ input power, so rearrange this to find how much electrical power must go in • Electrical power formula: P = V × I to connect power, voltage, and current

💭 Think About

• First convert 3 HP into watts so you have the mechanical output power in standard units • Use the 85% efficiency to figure out the electrical input power (it must be higher than the output power) • Once you know input power in watts and the voltage (100 V), solve P = V × I for current I

✅ Before You Answer

• Be sure you use output power ÷ efficiency to find the input power, not the other way around • Check that your final input power is larger than the 3 HP (in watts), since efficiency is less than 100% • After finding current, see which option is closest to Input power (W) ÷ 100 V and matches your units (amps)