Efficiency of electric motor is always less thana)75%b)100%c)50%d)25%Correct answer is option 'B'. Can you explain this answer?

Question

Answer

Efficiency of electric motor is always less than  100% because the output work is always less than the input work because some of the input work is used to overcome friction.

Answer

Electric motors have an efficiency of less than 100% because there is ALWAYS energy loss through any mechanism imaginable.

Answer

Efficiency of Electric Motor

The efficiency of an electric motor is a measure of how effectively it can convert electrical energy into mechanical energy. It is expressed as a percentage and indicates the proportion of input energy that is converted into useful output energy.

Efficiency Formula:

Efficiency (%) = (Output Power / Input Power) × 100

Explanation of the Correct Answer (Option B: 100%):

The statement in option B that the efficiency of an electric motor is always less than 100% is correct. This is because all electric motors have some energy losses due to various factors, which prevent them from achieving perfect efficiency.

Reasons for Electric Motor Efficiency Lower than 100%:

1. Electrical Losses:
- Copper Losses: These losses occur due to the resistance of the motor windings, resulting in the conversion of electrical energy into heat.
- Iron Losses: These losses occur due to the magnetic properties of the motor's core material, causing energy losses in the form of hysteresis and eddy currents.

2. Mechanical Losses:
- Friction and Windage Losses: These losses occur due to friction between moving parts and the air resistance faced by the motor.
- Bearing Losses: These losses occur due to friction within the motor's bearings.

3. Magnetic Losses:
- Eddy Current Losses: These losses occur due to the production of circulating currents in the motor's core material, resulting in energy dissipation.

4. Other Losses:
- Efficiency losses can also occur due to factors such as stray losses, harmonic losses, and cooling losses.

Consequence of Efficiency Less than 100%:

Due to these energy losses, an electric motor can never achieve 100% efficiency. The wasted energy is dissipated as heat, resulting in energy inefficiency and reduced overall performance. The higher the efficiency of an electric motor, the lower the energy losses and the better its performance.

Conclusion:

In conclusion, the efficiency of an electric motor is always less than 100% due to various energy losses that occur during its operation. These losses include electrical losses, mechanical losses, magnetic losses, and other losses. Understanding and improving motor efficiency is important to maximize energy utilization and reduce energy waste.

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