The heat engine receives 250 J of heat from the heater per cycle and gives the refrigerator 100 J of heat.

The heat engine receives 250 J of heat from the heater per cycle and gives the refrigerator 100 J of heat. Find the motor efficiency.

To find the efficiency of the motor, we will apply the formula to find the efficiency of the closed loop.

But we will start with a short record given:

Q1 = 250 J;

Q2 = 100 J;

To find:

Efficiency -?

Decision:

We know that the heat engine receives per cycle from the heater Q1 = 250 J of heat and, at the same time, gives the refrigerator Q2 = 100 J of heat.

Closed-loop efficiency:

Efficiency = (Q1 – Q2) / Q1 * 100%.

We just have to substitute the values into the formula and make calculations:

Efficiency = (250 – 100) / 250 * 100% = 60%.

Answer: 60%.