Question: State two reasons why efficiency is not 100%.

Linda Kokwaro answered on 18 May 2022:

Efficiency can be calculated as useful output/ energy in. Based on the 2nd law of thermodynamics, the natural tendancy is that entropy is always increasing. This means that all energy cannot be transferred into useful work due to loss in form of heat , friction, resistance in electrical devices etc, hence most devices/machines are not 100% efficient