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A Carnot engine used first ideal monoatomic gas and then an ideal diatomic gas, if the source and sink temperatures are 411 and 69, respectively and the engine extract 1000 J of heat from the source in each cycle, then

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Important Questions on Thermodynamics

MEDIUM
Three Carnot engines operate in series between a heat source at a temperature T1 and a heat sink at temperature T4 (see figure). There are two other reservoirs at temperature T2 and T3, as shown, with T1>T2>T3>T4. The three engines are equally efficient if:

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EASY
The coefficient of performance of a refrigerator is 5. If the temperature inside the freezer is -20 °C, the temperature of the surrounding to which it rejects heat is:
HARD
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, T1 and T2 . The temperature of the hot reservoir of the first engine is T1 and the temperature of the cold reservoir of the second engine is T2. 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 T1 and T2, if both the engines perform an equal amount of work?
EASY
A refrigerator works between 4C and 30oC. It is required to remove 600 calories of heat every second in order to keep the temperature of the refrigerated space constant. The power required is:

(Take 1 cal = 4.2 Joules)
EASY
A Carnot's engine having an efficiency of 110 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
EASY
If minimum possible work is done by a refrigerator in converting 100 grams of water at 0 °C to ice, how much heat (in calories) is released to the surroundings at temperature 27 °C (Latent heat of ice= 80 Cal/gram) to the nearest integer?
EASY
A Carnot engine having an efficiency of 110 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

Helium gas goes through a cycle ABCDA (consisting of two isochoric and two isobaric lines) as shown in figure. The efficiency of this cycle is approximately

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MEDIUM
A Carnot freezer takes heat from water at 0oC inside it and rejects it to the room at a temperature of 27oC. The latent heat of ice is 336×103 Jkg-1. If 5kg of water at 0oC is converted into ice at 0oC by the freezer, then the energy consumed by the freezer is close to :
EASY
A Carnot engine operates between two reservoirs of temperatures 900K and 300K . The engine performs 1200J of work per cycle. The heat energy (in J ) delivered by the engine to the low temperature reservoir, in a cycle, is _____________
EASY

An engine operates by taking a monatomic ideal gas through the cycle shown in the figure. The percentage efficiency of the engine is close to

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EASY
A Carnot engine, having an efficiency of η=110 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
The efficiency of a Carnot engine depends upon
MEDIUM
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
A reservoir is at 827 °C and Carnot's engine takes a thousand kilocalorie 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
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 is
EASY
An air conditioner AC removes heat at a rate of 1.2 kJ sec-1 from a room. A power of 400 W is required to run the AC. The coefficient of performance (α) of the AC is 10% of that of the refrigerator operating between outside and room temperature. If outside temperature is 37 °C, what will be room temperature?
MEDIUM
A Carnot engine has an efficiency of 16. When the temperature of the sink is reduced by 62  , its efficiency is doubled. The temperatures of the source and the sink are, respectively,
EASY
The temperature inside a refrigerator is t2 oC and the room temperature is t1 oC. The amount of heat delivered to the room for each joule of electrical energy consumed ideally will be
EASY
Two carnot engines A and B are operated in series. The first one, A, receives heat at T1=600K and rejects to a reservoir at temperature T2. The second engine B receives heat rejected by the first engine and, in turn, rejects to a heat reservoir at T3=400K. Calculate the temperature T2 if the work outputs of the two engines are equal: