Consider a system of N atoms of an ideal gas of type A at temperature T and volume V. It is kept in diffusive contact with another system of N atoms of another ideal gas of type B at the same temperature T and volume V. Once the combined system reaches equilibrium.
The correct answer is: entropy of final system is equal to the sum of individual entropies
The efficiency of a reversible heat engine performing the cyclic is
For the thermodynamics process shown in the figure, corresponding T-S diagram is
The T–S diagram of two cycles for the operation of an engine are shown in figure below.
The numerical values of the parameters T1 , T2 , S1 and S2 in the two figures are the same, then which cycle has greater efficiency?
Available energy per cycle is
Q1 – Q2 = Area of curve (ABC)
Q1 = Total area of curve (ABED)
⇒ Area of curve is same for both figures, but total area is more for Fig. 1.
Hence, second figure has greater efficiency.
The correct answer is: Second
An electric current of 3A flows through a resistance of 10 ohm. It is being cooled by running water and is kept at temperature 300K, change in entropy per second of the resistance :
There is no change in the entropy of the resistance because there is no change in the state of wire.
The correct answer is: No change
Out of three Carnot engines, operating between reservoir temperature of (a) 400 and 500 K (b) 600 and 800 K (c) 400 and 600 K, which has the greater thermal efficiency?
A reversible engine cyclic is shown in the following T–S diagram. The efficiency of the engine is :
In given figure, available energy per cycle is
and Q1 = 3T1S1
The correct answer is: 1/3
An engine absorbs heat at temperature of 1000 K and rejects heat at 600 K. If the engine operates at maximum possible efficiency, the amount of work performed by the engine for 200 J heat input is
An amount of heat Q is transferred from a heat reservoir at temperature TA to another heat reservoir at temperature TB. What is the change in the entropy Δs of the combined system?
Conventionally, heat given to the system is taken to be positive and heat extracted from the system is taken to be negative.
When heat is changed in the system entropy changed by an amount,
∴ For A
Similarly for B,
ΔS = ΔSA + ΔSB
The correct answer is:
The difference in entropy between a state of volume Vi and a state of volume Vf (temperature and number of molecules remaining constant) is equal to :