Even Carnot engine cannot give 100% efficiency, because we cannot
prevent radiation
find ideal sources
reach absolute zero temperature
eliminate friction
A Carnot engine, having an efficiency of 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
1 J
90 J
99 J
100 J
A diatomic ideal gas is used in a Carnot engine as the working substance. If during the adiabatic expansion part of the cycle the volume of the gas increased from V to 32 V, the efficiency of the engine is
0.25
0.5
0.75
0.99
A thermodynamic process is shown in the figure. The pressure and volumes corresponding to some points in the figure are
PA = 3 × 104 Pa, VA = 2 × 10-3 m3
PB = 8 × 104 Pa, VB = 5 × 10-3 m3
In process AB, 600 J of heat is added to the system and in process BC, 200 J of heat is added to the system. The change in internal energy of the system in process AC would be
560 J
800 J
600 J
640 J
The temperature-entropy diagram of a reversible engine cycle is given in the figure. Its efficiency is
1/3
1/2
2/3
1/4
When a system is taken from the initial state i to final state f along he path iaf, it is found that Q = 50 cal and W = 20 cal. If along the path ibf, Q = 36 cal, then W along the path ibf is
6 cal
16 cal
66 cal
14 cal
Which of the following statement is correct for any thermodynamic system ?
The internal energy changes in all processes
Internal energy and entopy are state functions
The change in entropy can never be zero
The work done in an adiabatic process is always zero.
Which of the following is not a thermodynamic coordinate?
P
V
T
R
One mole of an ideal gas at an initial temperature of T K does 6R joules of work adiabatically. If the ratio of specific heats of this gas at constant pressure and at constant volume is 5/3, the final temperature of gas will be
(T + 2.4)K
(T - 2.4)K
(T + 4)K
(T - 4)K
An ideal gas initially at P1, V1 is expanded to P2, V2 and then compressed adiabatically to the same volume V1 and pressure P3. If W is the net work done by the gas in complete process, which of the following is true ?
W > 0 ; P3 > P1
W < 0 ; P3 > P1
W > 0 ; P3 < P1