No external input is needed.

External energy must be expended.

The process reverses itself spontaneously.

The second law of thermodynamics must be violated.

Energy can be created or destroyed.

Identical quantities of energy are involved regardless of the feasibility of the process.

Energy flows only in one direction.

Energy conversion is not possible.

The first law of thermodynamics prevents it.

Friction causes energy losses during the process.

Water cannot be collected in a water wheel.

The second law of thermodynamics allows it to happen.

Heat flows spontaneously from a low temperature to a high temperature.

Heat flows spontaneously from a high temperature to a low temperature.

Heat flow direction is irrelevant to the second law of thermodynamics.

Heat flow violates the first law of thermodynamics.

The degradation of energy into less useful forms

The conversion of energy from one form to another

The direction of processes and how much heat is converted into work

The concept of heat reservoirs

Heat energy can be completely converted into work energy

Work energy can be completely converted into heat energy

Heat and work are completely interchangeable forms of energy

Energy transfer always increases the usefulness of energy

The conversion of energy from one form to another

The degradation of energy into more useful forms

The direction processes may take and how much heat is converted into work

The stability of heat reservoirs

A system that can transfer finite amounts of heat without changing its temperature

A system that always increases in temperature during heat transfer

A system that converts all heat into work energy

A system that only absorbs heat but does not release it

Heat sink

Heat source

Thermal equilibrium

Energy converter

Heat source

Heat sink

Thermal equilibrium

Energy converter

A system that undergoes a thermodynamic cycle.

A sufficiently large system in stable equilibrium to which and from which finite amounts of work can be transferred adiabatically without any change in its pressure.

A system that delivers net work in a thermodynamic cycle.

A system that undergoes a series of processes to constitute a heat engine cycle.

The properties of the system change completely.

The properties of the system remain the same as at its beginning.

The system loses energy.

The system gains energy.

P_f = P_i, T_f = T_i, u_f = u_i, v_f = v_i

P_f > P_i, T_f > T_i, u_f > u_i, v_f > v_i

P_f < P_i, T_f < T_i, u_f < u_i, v_f < v_i

P_f ≠ P_i, T_f ≠ T_i, u_f ≠ u_i, v_f ≠ v_i

A system that remains in stable equilibrium.

A thermodynamic system operating in a thermodynamic cycle to which net heat is transferred and from which net work is delivered.

A system that undergoes a thermodynamic cycle but does not deliver work.

A system that only transfers heat without undergoing a cycle.

A single process.

A series of processes that constitute the heat engine cycle.

No processes.

Only adiabatic processes.

The ratio of the heat input to the net work output

The ratio of the net work output to the heat input

The difference between the heat input and the heat output

The sum of the net work output and the heat input

It is always greater than 1

It is always equal to 1

It is always less than 1 or less than 100 percent

It is always equal to 0

The heat input

The heat output

The net work done

The energy lost to the surroundings

The heat supplied to make the cycle operate

The net work output

The energy lost to the atmosphere

The energy stored in the system

The direction of the process (positive or negative)

The magnitude of work or heat transfer (positive value)

The type of energy transfer (heat or work)

The efficiency of the system

$Q_{net,in} = W_{net,out}$

$Q_{net,in} > W_{net,out}$

$Q_{net,in} < W_{net,out}$

$Q_{net,in} + W_{net,out} = 0$

$W_{net,out} = Q_{in} + Q_{out}$

$W_{net,out} = Q_{in} - Q_{out}$

$W_{net,out} = Q_{out} - Q_{in}$

$W_{net,out} = Q_{in} \times Q_{out}$

$$\eta_{th} = \frac{Q_{in}}{W_{net,out}}$$

$$\eta_{th} = \frac{W_{net,out}}{Q_{in}}$$

$$\eta_{th} = \frac{Q_{out}}{Q_{in}}$$

$$\eta_{th} = \frac{Q_{in} - Q_{out}}{Q_{in}}$$

η_th = Q_out / Q_in

η_th = 1 - (Q_out / Q_in)

η_th = Q_in / Q_out

η_th = Q_in - Q_out

High-pressure and low-pressure reservoirs

High-temperature and low-temperature reservoirs

High-energy and low-energy reservoirs

High-volume and low-volume reservoirs

The temperature of the low-temperature reservoir

The temperature of the high-temperature reservoir

The total heat input to the system

The work output of the system

To transfer heat from a low-temperature reservoir to a high-temperature reservoir

To convert heat into work

To store thermal energy

To maintain constant temperature in both reservoirs

Diagram illustrating a heat engine operating between a high-temperature reservoir at T_H and a low-temperature reservoir at T_L.

Diagram illustrating a heat engine operating between two reservoirs at the same temperature.

Diagram illustrating a heat engine operating only at a low temperature reservoir at T_L.

Diagram illustrating a heat engine operating without any temperature reservoirs.

$$\eta_{th} = 1 - \frac{Q_H}{Q_L}$$

$$\eta_{th} = \frac{Q_L}{Q_H}$$

$$\eta_{th} = 1 - \frac{Q_L}{Q_H}$$

$$\eta_{th} = \frac{Q_H}{Q_L}$$

25%

33.3%

50%

66.7%

50 MW

100 MW

150 MW

200 MW

\( W_{net, out} = Q_H + Q_L \)

\( W_{net, out} = Q_H - Q_L \)

\( W_{net, out} = Q_L - Q_H \)

\( W_{net, out} = Q_H \times Q_L \)

$$\eta_{th} = 1 - \frac{Q_L}{Q_H}$$

$$\eta_{th} = \frac{Q_L}{Q_H}$$

$$\eta_{th} = \frac{Q_H}{Q_L}$$

$$\eta_{th} = 1 - \frac{Q_H}{Q_L}$$

To transfer heat from a high-temperature body to a low-temperature body

To transfer heat from a low-temperature body to a high-temperature body

To generate electricity from heat energy

To cool down a high-temperature body without external energy

Solar energy

Electrical energy or work

Chemical energy

Nuclear energy

A refrigerator operates without a thermodynamic cycle, while a heat pump does.

A refrigerator extracts heat from a high-temperature medium, while a heat pump extracts heat from a low-temperature medium.

A refrigerator rejects heat to a low-temperature medium, while a heat pump rejects heat to a high-temperature medium.

A refrigerator and a heat pump are identical in operation.

A device that generates heat without external energy

A cyclic device that transfers heat from a low-temperature body to a high-temperature body

A device that cools down a high-temperature body without a thermodynamic cycle

A device that operates only in high-temperature environments

The ratio of required input to desired result

The ratio of desired result to input

The difference between input and output

The sum of input and output

COP is always less than 1

COP measures the efficiency of a refrigerator or heat pump

COP is the ratio of heat rejected to heat absorbed

COP is independent of the desired result

To make COP as small as possible

To make COP equal to 1

To make COP as large as possible

To make COP equal to the input

COP = Required Input / Desired Result

COP = Desired Result / Required Input

COP = Desired Result - Required Input

COP = Required Input + Desired Result

To transfer heat from the high-temperature system to the low-temperature system

To transfer heat from the low-temperature system to the high-temperature system

To generate heat within the system

To cool the high-temperature system directly

The heat supplied at the high temperature

The heat supplied at the low temperature

The work done by the system

The cooling of the high-temperature environment

The ratio of work input to heat output

The ratio of heat supplied at low temperature to the net work input

The ratio of heat supplied at high temperature to the net work input

The ratio of net work input to heat supplied at low temperature

(Q_L - Q_H) - (0 - W_{in}) = \Delta U_{cycle} = 0

Q_H - Q_L = W_{in}

W_{in} = Q_H + Q_L

Q_L = Q_H - W_{in}

COP_R = $$\frac{Q_L}{Q_H - Q_L}$$

COP_R = $$\frac{Q_H}{Q_L - Q_H}$$

COP_R = $$\frac{Q_H}{W_{in}}$$

$$\frac{Q_L}{W_{in}}$$

To transfer heat to the high-temperature system.

To transfer heat to the low-temperature system.

To generate work from heat.

To maintain a constant temperature in the system.

COP_{HP} = $$\frac{Q_H}{Q_H - Q_L}$$

COP_{HP} = $$\frac{Q_L}{Q_H - Q_L}$$

COP_{HP} = $$\frac{Q_H}{W_{in}}$$

COP_{HP} = $$\frac{Q_L}{W_{in}}$$

COP_{HP} = COP_R + 1

COP_{HP} = COP_R - 1

COP_{HP} = COP_R

COP_{HP} = COP_R \times 2

The amount of cooling or heating on a seasonal basis per unit rate of power expended in watts

The maximum temperature a heat pump can achieve

The total energy consumption of a heat pump over a year

The efficiency of a heat pump at a single temperature

10,000 Btu/hr

12,000 Btu/hr

15,000 Btu/hr

20,000 Btu/hr

Heat engines can achieve 100% efficiency

Heat engines can produce a net amount of work while exchanging heat with a single reservoir

Heat engines cannot produce a net amount of work while exchanging heat with a single reservoir

Heat engines can operate without any heat exchange

100%

Less than 100%

50%

Greater than 100%

It is possible to construct a device that transfers heat from a lower-temperature body to a higher-temperature body without any external work.

It is impossible to construct a device that operates in a cycle and produces no effect other than the transfer of heat from a lower-temperature body to a higher-temperature body.

It is possible to construct a device that violates the Kelvin-Planck statement of the second law.

It is impossible to construct a device that operates in a cycle and transfers heat from a higher-temperature body to a lower-temperature body.

A heat engine that operates with 100% efficiency.

A heat engine that converts all the heat input into work output without any heat rejection.

A heat engine that transfers heat from a lower-temperature body to a higher-temperature body without external work.

A heat engine that operates in a cycle and rejects heat to a lower-temperature reservoir.

It ensures that the engine violates the Kelvin-Planck statement of the second law.

It indicates that some heat is rejected to the surroundings, making the engine realistic.

It means the engine operates without any heat input.

It shows that the engine transfers heat from a lower-temperature body to a higher-temperature body.

Heat can flow from a low-temperature medium to a high-temperature medium without any external work.

Heat pumps can operate with a coefficient of performance (COP) equal to infinity.

Energy in the form of work or heat must be expended to force heat to flow from a low-temperature medium to a high-temperature medium.

Heat pumps can violate the laws of thermodynamics under certain conditions.

Infinity

Zero

One

Five

Because the Clausius statement of the second law prohibits infinite efficiency.

Because heat naturally flows from high-temperature to low-temperature regions.

Because work is not required for heat transfer in a heat pump.

Because the second law of thermodynamics allows for infinite energy.

A violation of the Clausius statement.

The heat engine operates with 100% efficiency.

Heat is transferred from a high-temperature reservoir to a low-temperature reservoir.

Work is produced without any heat input.

Q_H + Q_L

Only Q_H

Only Q_L

Work W

Heat is transferred from a low-temperature reservoir to a high-temperature reservoir without external energy input.

Work is produced without any heat input.

Heat is transferred from a high-temperature reservoir to a low-temperature reservoir.

The heat engine operates with 100% efficiency.

A device that violates the second law of thermodynamics.

A device that violates the first law of thermodynamics.

A device that operates without any energy input.

A device that follows both the first and second laws of thermodynamics.

It is a process that cannot be reversed.

It is a quasi-equilibrium process with a restrictive requirement.

It is a process that violates the second law of thermodynamics.

It is a process that leaves permanent changes in the system.

Internally reversible processes leave no change in the surroundings.

Externally reversible processes leave no change in the system.

Internally reversible processes leave no change in the system, but not necessarily in the surroundings.

Externally reversible processes cannot be reversed.

The process cannot be reversed.

The process leaves no change in the system or surroundings.

The process leaves changes only in the surroundings.

The process violates the first law of thermodynamics.

A process that can be reversed without any loss of energy

A process that is not reversible

A process that occurs only in ideal conditions

A process that involves no heat transfer

Friction

Unrestrained expansion of gases

Perfectly insulated systems

Heat transfer through a finite temperature difference

A French physicist who discovered the first law of thermodynamics

A French military engineer who studied the second law of thermodynamics

A German scientist who introduced the concept of entropy

An English mathematician who developed the concept of heat engines

Two reversible processes and two irreversible processes

Four irreversible processes

Four reversible processes, two isothermal and two adiabatic

Two isothermal processes and two constant pressure processes

A perfectly insulated system

Frictionless motion

Mixing of two different substances

A quasi-static process

Reversible adiabatic expansion decreases the working fluid temperature.

Reversible isothermal heat addition at high temperature to the working fluid.

The system is brought in contact with a heat reservoir at low temperature.

Reversible adiabatic compression increases the working fluid temperature.

It increases from TL to TH.

It remains constant.

It decreases from TH to TL.

It oscillates between TH and TL.

It provides heat to the system at high temperature.

It absorbs heat from the system at low temperature.

It facilitates reversible adiabatic expansion.

It increases the working fluid temperature from TL to TH.

The working fluid temperature decreases from TH to TL.

The working fluid temperature increases from TL to TH.

The system performs boundary work.

The system undergoes isothermal heat exchange.

Process 1-2

Process 2-3

Process 3-4

Process 4-1

Clockwise

Counterclockwise

Random

Vertical

A refrigerator

A heat engine

A turbine

A compressor

Counterclockwise

Clockwise

Horizontal

Random

A heat engine can operate by exchanging heat with a single heat reservoir.

A refrigerator can operate without net work input from an external source.

A heat engine cannot operate by exchanging heat with a single heat reservoir.

A refrigerator can operate without any energy input.

The efficiency of an irreversible heat engine is greater than that of a reversible one.

The efficiency of an irreversible heat engine is equal to that of a reversible one.

The efficiency of an irreversible heat engine is always less than that of a reversible one.

The efficiency of an irreversible heat engine is independent of the reservoirs.

They have different efficiencies depending on the working substance.

They have the same efficiency.

Their efficiency depends on the external work input.

Their efficiency is always less than that of irreversible heat engines.

He discovered the Carnot principles.

He defined temperature using energy as a thermodynamic property.

He invented the first heat engine.

He proved that reversible heat engines are less efficient than irreversible ones.

η_th = Q_H / Q_L

η_th = 1 - Q_L / Q_H

η_th = Q_L / Q_H

η_th = 1 + Q_L / Q_H

η_th = g(T_H, T_L) = 1 - f(T_H, T_L)

η_th = g(T_L, T_H) = 1 - f(T_L, T_H)

η_th = g(T_H, T_L) = 1 + f(T_H, T_L)

η_th = g(T_L, T_H) = 1 + f(T_L, T_H)

Otto engine

Carnot engine

Diesel engine

Stirling engine

θ(T₁) = T₁ / T₃

θ(T₃) = T₃ / T₁

θ(T₁) = T₁²

θ(T₃) = T₃²

The maximum possible efficiency of a heat engine operating between two heat reservoirs.

The average efficiency of a heat engine.

The minimum efficiency of a heat engine.

The efficiency of a heat engine at room temperature.

ηₜₕ,ₐ = 1 - Tₗ / Tₕ

ηₜₕ,ₐ = Tₗ / Tₕ

ηₜₕ,ₐ = Tₕ / Tₗ

ηₜₕ,ₐ = 1 + Tₗ / Tₕ

The ratio of absolute temperatures.

The product of θ(T₃) and θ(T₁).

The ratio of θ(T₃) to θ(T₁).

The sum of θ(T₃) and θ(T₁).

The pressure difference between two reservoirs

The heat transfers between a reversible device and the high- and low-temperature heat reservoirs

The volume change in a heat engine

The speed of heat transfer in a system

$ T_H / T_L $

$ T_L / T_H $

$ Q_L / Q_H $

$ T_H - T_L $

When the heat exchange occurs with varying temperature reservoirs

When the heat exchange occurs across a heat engine operating between two constant temperature heat reservoirs

When the heat exchange occurs with heat sources and sinks that do not have constant temperature

When the heat engine operates at maximum speed

$ \eta_h > \eta_{h,rev} $ for all heat engines

$ \eta_h = \eta_{h,rev} $ for irreversible heat engines

$ \eta_h < \eta_{h,rev} $ for irreversible heat engines

$ \eta_h > \eta_{h,rev} $ for reversible heat engines

$ \eta_h < \eta_{h,rev} $

$ \eta_h = \eta_{h,rev} $

$ \eta_h > \eta_{h,rev} $

$ \eta_h = 0 $

Coefficient of Pressure

Coefficient of Performance

Coefficient of Power

Coefficient of Potential

It becomes a heat engine.

It becomes a reversible heat pump.

It stops functioning.

It becomes a refrigerator.

COP_R = $$\frac{T_H}{T_H - T_L}$$

COP_R = $$\frac{T_L}{T_H - T_L}$$

COP_R = $$\frac{T_H}{T_L}$$

COP_R = $$\frac{T_L}{T_H}$$