Question

If the efficiency of a coal-fired electrical generating plant is 35%, then what do we mean when we say that energy is a conserved quantity?

Short answer

According to the law of conservation of energy, energy is a conserved quantity.

Step-by-step solution

Definition of Concepts 

Efficiency:The term efficiency is defined as the ratio of the total useful output energy to the total input energy.

Mathematically, the efficiency is given as,

$\text{Efficiency}=\frac{\text{Total useful output energy}}{\text{Total input energy}}$

Explain the efficiency of a coal-fired electrical generating plant

If the efficiency of the coal-fired electrical generating plant is $35\%$, which means that only$35\%$ of the heat energy is getting converted into electrical energy, while the remaining$65\%$ of the heat energy is dissipated into other forms of energy.

As the total input heat energy in the system is converted into electrical energy and other forms of energy. Therefore, energy is a conserved quantity.