Question

Assertion : The Carnot cycle is useful in understanding the performance of heat engines.
Reason : The Carnot cycle provides a way of determining the maximum possible efficiency achievable with reservoirs of given temperatures.

• A. If both assertion and reason are true and reason is the correct explanation of the assertion
• B. If both assertion and reason are true but reason is not the correct explanation of the assertion
• C. If assertion is true, but reason is false
• D. Both assertion and reason are false statements

Answer 1

Answer: (A)

A heat engine, or more simply, an engine is a device that extracts energy from its environment in the form of heat and does useful work. We choose to study real engines by analyzing the behaviour of ideal engines. A particular ideal engine called a Carnot engine serves as ideal heat engine. This ideal engine turns out to be the best at using energy as heat to do useful work. Carnot engine comprises four cycles. During each cycle of engine, the working substance absorbs energy $\left|Q_H\right|$ as heat from a thermal reservoir at constant temperature $T_H$ and discharges energy $\left|Q_L\right|$ as heat to a second thermal reservoir at a constant lower temperature $T_L$. Thus, Carnot cycle provides a way of determining the maximum possible efficiency achievable with reservoirs of given temperaturs.