MEDIUM

Earn 100

The compressor of a Carnot refrigerator consumes $5 J$ of energy per cycle. The hot reservoir is at temperature $27 ° C$ and the amount of energy released to it per cycle is $25 J$ . Then the lowest possible temperature attained by the cold reservoir will be close to

75% studentsanswered this correctly

Important Questions on Heat and Thermodynamics

EASY

Physics>Heat and Thermodynamics>Heat and Thermodynamics>Refrigerators and Heat Pumps

A Carnot heat engine having an efficiency of

\frac{1}{10}

is used as a refrigerator between the same two temperatures. If the work done on the system is

10 J

, the amount of heat absorbed from the reservoir at low temperature is

MEDIUM

Physics>Heat and Thermodynamics>Heat and Thermodynamics>Refrigerators and Heat Pumps

A reservoir is at

827 ° C

and Carnot's engine takes a thousand

kilo calorie

of heat from it and exhausts it to a sink at

27 ° C

. What is the amount of work and the efficiency of the engine?

EASY

Physics>Heat and Thermodynamics>Heat and Thermodynamics>Refrigerators and Heat Pumps

Two carnot engines

A

and

B

are connected in series in such a way that the work outputs are equal when the temperatures of hot and cold reservoirs of

A

are

800 K

and

T

, and of engine

B

are

T

and

300 K

, respectively. Then the temperature

T

EASY

Physics>Heat and Thermodynamics>Heat and Thermodynamics>Refrigerators and Heat Pumps

Two carnot engines

A

and

B

are operated in series. The first one,

A,

receives heat at

T_{1} (= 600 K)

and rejects to a reservoir at temperature

T_{2} .

The second engine

B

receives heat rejected by the first engine and, in turn, rejects to a heat reservoir at

T_{3} (= 400 K) .

Calculate the temperature

T_{2}

if the work outputs of the two engines are equal:

EASY

Physics>Heat and Thermodynamics>Heat and Thermodynamics>Refrigerators and Heat Pumps

A Carnot engine having an efficiency of

\frac{1}{10}

is being used as a refrigerator. If the work done on the refrigerator is

10 J,

the amount of heat absorbed from the reservoir at a lower temperature is

MEDIUM

Physics>Heat and Thermodynamics>Heat and Thermodynamics>Refrigerators and Heat Pumps

Heat is flowing from a refrigerator whose inside temperature is

280 K

, to a room at

300 K

. Then the amount of heat delivered to the room for each joule of electrical energy consumed in joules is

EASY

Physics>Heat and Thermodynamics>Heat and Thermodynamics>Refrigerators and Heat Pumps

An air conditioner

(A C)

removes heat at a rate of

1.2 kJ \sec^{- 1}

from a room. A power of

400 W

is required to run the

A C

. The coefficient of performance

(α)

of the

A C

10 %

of that of the refrigerator operating between outside and room temperature. If outside temperature is

37 ° C

, what will be room temperature?

HARD

Physics>Heat and Thermodynamics>Heat and Thermodynamics>Refrigerators and Heat Pumps

The efficiency of the cycle shown below in the figure (consisting of one isobar, one adiabat and one isotherm) is $50 % .$ The ratio, $x,$ between the highest and lowest temperatures attained in this cycle obeys (the working substance is a ideal gas):-

Question Image

HARD

Physics>Heat and Thermodynamics>Heat and Thermodynamics>Refrigerators and Heat Pumps

Two ideal Carnot engines operate in a cascade (all heat given up by one engine is used by the other engine to produce work) between temperatures,

T_{1}

and

T_{2}

. The temperature of the hot reservoir of the first engine is

T_{1}

and the temperature of the cold reservoir of the second engine is

T_{2}

T

is the temperature of the sink of the first engine which is also the source for the second engine. How is

T

related to

T_{1}

and

T_{2}

, if both the engines perform an equal amount of work?

MEDIUM

Physics>Heat and Thermodynamics>Heat and Thermodynamics>Refrigerators and Heat Pumps

A heat engine is involved with exchange of heat of

1915 J, - 40 J, + 125 J

and

- Q J

, during one cycle achieving and efficiency of

50.0 %

. The value of

Q

is:

MEDIUM

Physics>Heat and Thermodynamics>Heat and Thermodynamics>Refrigerators and Heat Pumps

Freezing compartment of a refrigerator is at

0 ° C

and room temperature is

27.3 ° C

. Work done by the refrigerator to freeze

1 g

of water at

0 ° C

(L_{ice} = 80 cal g^{- 1})

EASY

Physics>Heat and Thermodynamics>Heat and Thermodynamics>Refrigerators and Heat Pumps

A Carnot's engine having an efficiency of

\frac{1}{10}

as heat engine, is used as a refrigerator. If the work done on the system is

10 J,

the amount of energy absorbed from the reservoir at lower temperature is

MEDIUM

Physics>Heat and Thermodynamics>Heat and Thermodynamics>Refrigerators and Heat Pumps

Consider an engine that absorbs

130 cal

of heat from a hot reservoir and delivers

30 cal

heat to a cold reservoir in each cycle. The engine also consumes

2 J

energy in each cycle to overcome friction. If the engine works at

90

cycles per minute, what will be the maximum power delivered to the load? [Assume the thermal equivalent of heat is

4.2 J / cal

]

EASY

Physics>Heat and Thermodynamics>Heat and Thermodynamics>Refrigerators and Heat Pumps

A Carnot engine, having an efficiency of

η = \frac{1}{10}

as heat engine, is used as a refrigerator. If the work done on the system is

10 J

, the amount of energy absorbed from the reservoir at a lower temperature is:

EASY

Physics>Heat and Thermodynamics>Heat and Thermodynamics>Refrigerators and Heat Pumps

A carnot engine working between

27 ° C

and

127 ° C,

draws

600 J

of heat from the reservoir in one cycle. The work done by the engine

EASY

Physics>Heat and Thermodynamics>Heat and Thermodynamics>Refrigerators and Heat Pumps

For a Carnot engine which of the following is false?

EASY

Physics>Heat and Thermodynamics>Heat and Thermodynamics>Refrigerators and Heat Pumps

A Carnot's engine working between

400 K

and

800 K

has a work output of

1200 J

per cycle. The amount of heat energy supplied to the engine from the source in each cycle is:

EASY

Physics>Heat and Thermodynamics>Heat and Thermodynamics>Refrigerators and Heat Pumps

The efficiency of a Carnot engine depends upon

MEDIUM

Physics>Heat and Thermodynamics>Heat and Thermodynamics>Refrigerators and Heat Pumps

A Carnot engine has an efficiency of

\frac{1}{6} .

When the temperature of the sink is reduced by

62 ℃

, its efficiency is doubled. The temperatures of the source and the sink are, respectively,

MEDIUM

Physics>Heat and Thermodynamics>Heat and Thermodynamics>Refrigerators and Heat Pumps

Three Carnot engines operate in series between a heat source at a temperature

T_{1}

and a heat sink at temperature

T_{4}

(see figure). There are two other reservoirs at temperature

T_{2}

and

T_{3},

as shown, with

T_{1} > T_{2} > T_{3} > T_{4} .

The three engines are equally efficient if:

Question Image

The compressor of a Carnot refrigerator consumes 5 J of energy per cycle. The hot reservoir is at temperature 27°C and the amount of energy released to it per cycle is 25 J. Then the lowest possible temperature attained by the cold reservoir will be close to

Important Questions on Heat and Thermodynamics

Learn and Prepare for any exam you want !

The compressor of a Carnot refrigerator consumes $5 J$ of energy per cycle. The hot reservoir is at temperature $27 ° C$ and the amount of energy released to it per cycle is $25 J$ . Then the lowest possible temperature attained by the cold reservoir will be close to