Question

Do devices with efficiencies of less than one violate the law of conservation of energy? Explain

Short answer

No, devices with an efficiency of less than one do not violate the law of energy conservation.

Step-by-step solution

Step 1: Definition of Concepts

Efficiency: Efficiency is defined as the ratio of the total useful power to the total input power.

Mathematically,

$\mathbf{\eta }\mathbf{=}\frac{\mathbf{total}\mathbf{}\mathbf{useful}\mathbf{}\mathbf{output}\mathbf{}\mathbf{power}}{\mathbf{total}\mathbf{}\mathbf{input}\mathbf{}\mathbf{power}}$

Here, $\mathbf{\eta }$is the efficiency.

Explain the devices with efficiencies of less than one violate the law of conservation of energy

For a nonconservative force, all the work done by the nonconservative force adds to the mechanical energy.

Apart from kinetic energy, potential energy, and the work done by all nonconservative forces, there are other forms of output energy that cannot be used. But efficiency takes into account only the useful output power.

Hence, the devices with an efficiency of less than one do not violate the law of conservation of energy.