Thermodynamics Ques 20
20. If $\Delta U$ and $\Delta W$ represent the increase in internal energy and work done by the system respectively in a thermodynamical process, which of the following is true? [2010, 1998]
(a) $\Delta U=-\Delta W$, in an adiabatic process
(b) $\Delta U=\Delta W$, in an isothermal process
(c) $\Delta U=\Delta W$, in an adiabatic process
(d) $\Delta U=-\Delta W$, in an isothermal process
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Answer:
Correct Answer: 20.(a)
Solution:
- (a) By first law of thermodynamics, $\Delta Q=\Delta U+\Delta W$ In adiabatic process, $\Delta Q=0$
$\therefore \Delta U=-\Delta W$
In isothermal process, $\Delta U=0$
$\therefore \Delta Q=\Delta W$
BETA
