How is motor efficiency expressed in percentage terms?

Motor efficiency is expressed as the ratio of useful work output to energy input. This measurement indicates how effectively a motor converts electrical energy into mechanical energy. In percentage terms, it is calculated by taking the useful output power (usually in watts) provided by the motor and dividing it by the input power (which is also measured in watts). The result is then multiplied by 100 to express it as a percentage.

This approach provides a clear understanding of how much of the electrical energy supplied to the motor is converted into useful work, which is essential for evaluating the performance and efficiency of motors in various applications. A high motor efficiency percentage indicates that the motor is performing well with minimal losses, which is crucial for energy conservation and cost-effectiveness in industrial processes.

The other options do not correctly describe motor efficiency in the context of its traditional definition and measurement. Heat loss, coefficient of performance, and the relationship of torque to speed pertain to different concepts in the field of motors and energy use, but they do not directly represent the efficiency calculation as outlined.