The temperature-entropy diagram of a reversible engine cycle is given in the figure. Its efficiency is:
A Carnot engine whose sink is at 300 K has an efficiency of 40%. By how much should the temperature of source be increased so as to increase its efficiency by 50% of original efficiency?
The molar specific heat at constant pressure of an ideal gas is (7/2)R. The ratio of specific heat at constant pressure to that at constant volume is
Which one of the following is not a state function ?
A monoatomic ideal gas, initially at temperature T1 is enclosed in a cylinder fitted with a friction-less piston. The gas is allowed to expand adiabatically to a temperature T2 by releasing the piston suddenly. L1 and L2 are the lengths of the gas column before and after expansion respectively, then T1/T2 is given by:
(L1 / L2) 2/3
(L1 / L2)
(L2 / L1)
(L2 / L1)2/3
In thermodynamic processes which of the following statements is not true?
In an adiabatic process the system is insulated from the surroundings
In an isochoric process pressure remains constant
In an isothermal process the temperature remains constant
In an adiabatic process pVγ = constant
An ideal gas is taken through the cycle A B C A as shown in the figure. If the net heat supplied to the gas in the cycle is 5 J, the work done by the gas in the process C A is:
- 5 J
- 10 J
- 15 J
- 20 J
A scientist says that the efficiency of his heat engine which works at source temperature of 127oC and sink temperature 27oC is 26%.
It is impossible
It is possible but less probable
It is quite possible
Data is incomplete
A Carnot engine operating between temperatures T1 and T2 has efficiency 1/6. When T2 is lowered by 62 K, its efficiency increases to 1/3. Then T1 and T2 are, respectivley:
372 K and 310 K
372 K and 330 K
330 K and 268 K
310 K and 248 K
Initial pressure and volume of a gas are P and V respectively. First the gas is expanded isothermally to 4V and then its volume is made V by adiabatic process. Its final pressure (γ = 1.5) is