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For which combination of temperatures, the efficiency of Carnot's engine is highest?

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Important Questions on The First Law of Thermodynamics

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Complete Study Pack for Engineering Entrances Objective Physics Vol 1>Chapter 15 - The First Law of Thermodynamics>Objective Problems>Q 68

Two carnot engines

A

and

B

are operated in succession. The first one,

A

receives heat from a source at

T_{1} = 800 K

and rejects to the sinks at

T_{2} K

. The second engine

B

receives heat rejected by the first engine and then rejects to another sink at

T_{3} = 300 K

. If the work outputs of the two engines are equal, then the value of

T_{2}

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Complete Study Pack for Engineering Entrances Objective Physics Vol 1>Chapter 15 - The First Law of Thermodynamics>Objective Problems>Q 69

A carnot's engine whose low temperature reservoir is at

7 ° C

has an efficiency of

50 %

. It is desired to increase the efficiency to

70 %

. By how many degrees should the temperature of the high temperature reservoir be increased?

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Complete Study Pack for Engineering Entrances Objective Physics Vol 1>Chapter 15 - The First Law of Thermodynamics>Objective Problems>Q 70

Six moles of an ideal gas performs a cycle shown in the figure. If the temperatures are $T_{A} = 600 K, T_{B} = 800 K$ , $T_{C} = 2200 K$ and $T_{D} = 1200 K,$ then work done per cycle is approximately___ (Take $R = 8.3 J {mol}^{- 1} K^{- 1}$ )

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Complete Study Pack for Engineering Entrances Objective Physics Vol 1>Chapter 15 - The First Law of Thermodynamics>Objective Problems>Q 71

A Carnot's engine is made to work between

200 ° C

and

0 ° C

first and then between

0 °

and

- 200 ° C

. The ratio of efficiencies

(\frac{η_{2}}{η_{1}})

of the engine in the two cases is

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Complete Study Pack for Engineering Entrances Objective Physics Vol 1>Chapter 15 - The First Law of Thermodynamics>Objective Problems>Q 72

The process

Δ U = 0

, for an ideal gas can be best represented in the form of a graph

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Complete Study Pack for Engineering Entrances Objective Physics Vol 1>Chapter 15 - The First Law of Thermodynamics>Objective Problems>Q 74

When an air bubble rises from the bottom to the surface of a lake, its radius becomes double. Find the depth of the lake. Given that the atmospheric pressure is equal to the pressure due to a column of water

10 m

high. Assume constant temperature and disregard surface tension

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Complete Study Pack for Engineering Entrances Objective Physics Vol 1>Chapter 15 - The First Law of Thermodynamics>Objective Problems>Q 75

Two identical containers joined by a small pipe initially contain the same gas at pressure

p_{0}

and absolute temperature

T_{0}

. One container is now maintained at the same temperature while the other is heated to

2 T_{0}

. The common pressure of the gases will be

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Complete Study Pack for Engineering Entrances Objective Physics Vol 1>Chapter 15 - The First Law of Thermodynamics>Objective Problems>Q 76

An ideal monoatomic gas is compressed (no heat being added or removed in the process) so that its volume is halved. The ratio of the new pressure to the original pressure is

For which combination of temperatures, the efficiency of Carnot's engine is highest?

Important Questions on The First Law of Thermodynamics

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