MCQ
The $P-V$ diagram of $2$ gm of helium gas for a certain process $A \to B$ is shown in the figure. what is the heat given to the gas during the process $A \to B$
  • A
    $4{P_o}{V_o}$
  • $6{P_o}{V_o}$
  • C
    $4.5{P_o}{V_o}$
  • D
    $2{P_o}{V_o}$

Answer

Correct option: B.
$6{P_o}{V_o}$
b
(b) Change in internal energy from $A \to B$ is

$\Delta U = \frac{f}{2}\mu R\Delta T = \frac{f}{2}({P_f}{V_f} - {P_i}{V_i})$

$ = \frac{3}{2}(2{P_0} \times 2{V_0} - {P_0} \times {V_0}) = \frac{9}{2}{P_0}{V_0}$

Work done in process $A \to B$ is equal to the Area covered by the graph with volume axis i.e.,

${W_{A \to B}} = \frac{1}{2}({P_0} + 2{P_0}) \times (2{V_0} - {V_0}) = \frac{3}{2}{P_0}{V_0}$

Hence, $\Delta Q = \Delta U + \Delta W$$ = \frac{9}{2}{P_0}{V_0} + \frac{3}{2}{P_0}{V_0} = 6{P_0}{V_0}$

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