Answer:
The efficiency of the hair dryer is 0.2 or 20%
Explanation:
The efficiency of a machine or any appliance is a measure of the useful work done by the machine when an effort is applied to the machine. The higher the efficiency of a machine, the more useful work the machine does.
Due to the economical and environmental impact of energy production, machines and appliances of high efficiency are being developed and recommended for domestic as well as industrial use nowadays.
In electrical appliances, energy is usually supplied by electrical power units. The higher the efficiency of an electrical appliance, the less power it consumes to do useful work. For a hair dryer which takes in 3000 J of energy per second and transfers 600 J of useful heat energy, its efficiency is calculated with formula below:
efficiency = useful energy / total energy input
Efficiency = 600 J / 3000 J = 0.2
Therefore, the efficiency of the hair dryer is 0.2 or 20%
