The efficiency of a fan is defined as its ____________ divided by its __________.

The efficiency of a fan is a measure of how effectively it converts input power into useful work output. In this context, efficiency is defined as the ratio of power output to power input. This indicates how much of the electrical energy supplied to the fan is transformed into kinetic energy of airflow – the desired output.

When you calculate fan efficiency, you focus on how much of the input power is actually utilized in delivering air movement compared to what is consumed. This is important because not all the energy from the input is converted into useful output; some energy may be lost as heat due to friction and other factors. Therefore, the definition involving power output divided by power input provides a clear understanding of a fan's performance and effectiveness in air distribution systems.