Question

What is the formula for calculating the efficiency of a heat engine?

Answer 1

Answer: The correct answer is $Efficiency= \frac{W}{Q_{H}}$.

Explanation:

Heat engine: It is a device which converts the heat energy in to the mechanical work. In heat engine, the heat is transferred from high temperature reservoir to the low temperature reservoir.

It is just opposite of the refrigeration.

The expression of the work done is as follows;

$W=Q_{H}-Q_{C}$

Here, $Q_{H}$ is the heat added to the system and $Q_{C}$ is the heat rejected to the cold reservoir.

The formula for calculating the efficiency of a heat engine is as follows;

$Efficiency= \frac{W}{Q_{H}}$

Here, W is the work done and $Q_{H}$ is the heat added from the reservoir which is at high temperature and $Q_{C}$ is the heat rejected to the reservoir which is at low temperature.

Answer 2

Hi there,


Efficiency=. Work
——————-
Heat energy

We know that all the energy that is put into the engine has to come out either as work or waste heat. So work is equal to Heat at High temperature minus Heat rejected at Low temperature.