Heat Engines and Refrigerators
Physics ⇒ Heat and Thermodynamics
Heat Engines and Refrigerators starts at 11 and continues till grade 12.
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Describe the main difference between a heat engine and a refrigerator.
Describe the role of the working substance in a heat engine.
Explain why a refrigerator must do work to transfer heat from a cold region to a hot region.
Explain why no real engine can be 100% efficient.
A Carnot engine absorbs 1000 J of heat from a reservoir at 500 K and rejects heat to a reservoir at 300 K. How much work does it do?
A Carnot engine operates between 400 K and 300 K. What is its efficiency?
A Carnot refrigerator operates between 273 K and 313 K. What is its coefficient of performance (COP)?
A heat engine has an efficiency of 30%. If it absorbs 1500 J of heat, how much work does it do?
Which of the following best describes a heat engine? (1) A device that converts heat into work (2) A device that converts work into heat (3) A device that transfers heat from a cold reservoir to a hot reservoir (4) A device that stores thermal energy
Which of the following cycles is an idealized model for heat engines? (1) Otto cycle (2) Carnot cycle (3) Diesel cycle (4) Rankine cycle
Which of the following devices operates on the reverse principle of a heat engine? (1) Refrigerator (2) Steam engine (3) Gas turbine (4) Diesel engine
Which of the following is a correct expression for the coefficient of performance (COP) of a refrigerator? (1) COP = Qh/W (2) COP = Qc/W (3) COP = W/Qc (4) COP = W/Qh
The coefficient of performance (COP) of a refrigerator is defined as the ratio of ________ to the work input.
The efficiency of a Carnot engine is given by the formula ________.
The efficiency of a Carnot engine operating between two heat reservoirs depends only on the ________ of the reservoirs.
The efficiency of a heat engine is defined as the ratio of ________ to the heat absorbed from the hot reservoir.
True or False: In a Carnot cycle, all processes are reversible.
True or False: The Carnot cycle consists of two isothermal and two adiabatic processes.
True or False: The coefficient of performance of a refrigerator can be greater than 1.
True or False: The COP of a heat pump is always less than 1.
