Calculating Efficiency and Energy Transfers in Devices

The video tutorial explains how to calculate the efficiency of devices using Sankey diagrams, which illustrate energy transfers. It provides examples with a car engine, a light bulb, and an electric fan. The efficiency is calculated by dividing the useful energy output by the total energy output and multiplying by 100%. The tutorial demonstrates this process with detailed examples, showing how to identify useful and wasted energy forms and calculate efficiency percentages.

What percentage of energy supplied to the light bulb is considered useful energy?

Discuss the significance of wasted energy in the context of energy efficiency.

How is the useful energy output of an electric fan calculated based on its efficiency?