Efficiency of Electric Motors

What is the law of conservation of energy?

• Energy flows from negative to positive terminals in a circuit
• Energy can only be lost through resistance and friction
• Energy can neither be created nor destroyed, only transformed
• Energy can be created or destroyed, but not transformed

What type of energy does an electric motor convert into mechanical work?

• Thermal energy
• Kinetic energy
• Electrical energy
• Potential energy

What is the unit of work in the context of electric motors?

• Newton
• Joule
• Watt
• Ampere

What does the efficiency of an electric motor measure?

• The total energy input
• The amount of energy lost
• The ratio of useful output to input energy
• The speed of the motor

An electric motor has an input power of 200 W and an output power of 150 W. What is its efficiency?

• 50%
• 75%
• 100%
• 125%

If a motor supplies a force of 15 N and moves an object 2 m, what is the work done?

• 15 Nm
• 30 Nm
• 2 Nm
• 17 Nm

How is power calculated in electrical terms?

• Power = voltage × resistance
• Power = current × resistance
• Power = voltage × current
• Power = resistance × time

What is wasted energy in an electric motor often converted into?

• Light
• Magnetic energy
• Sound and heat
• Chemical energy

What is the main unit of energy?

• Newton
• Joule
• Watt
• Volt

What does 1 kWh represent?

• The power used by a 1 kW motor in 1 hour
• The energy used by a 1 kW motor in 1 hour
• The current used by a 1 kW motor in 1 hour
• The voltage used by a 1 kW motor in 1 hour