Sample interview questions: Discuss the concept of heat engines and their efficiency.
Sample answer:
Concept of Heat Engines:
- A heat engine is a device that converts heat into mechanical energy.
- It works by exploiting the difference in temperature between a hot reservoir and a cold reservoir.
- The hot reservoir provides heat to the engine, which is then used to do work.
- The cold reservoir absorbs heat from the engine, which is then expelled to the environment.
- The efficiency of a heat engine is the ratio of the work done by the engine to the heat absorbed from the hot reservoir.
Factors Affecting Efficiency:
- The efficiency of a heat engine is limited by the Carnot efficiency, which is the maximum possible efficiency for a heat engine operating between two reservoirs at different temperatures.
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The Carnot efficiency is given by:
η_C = 1 - T_C / T_H
where:- η_C is the Carnot efficiency
- T_C is the temperature of the cold reservoir
- T_H is the temperature of the hot reservoir
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The efficiency of a real heat engine is always less than the Carnot efficiency due to irreversibilities such as fr… Read full answer