Which of the following expressions gives the work done by an ideal gas when it…

PHYSICS · Single correct · A Level · Physics · Further mechanics and thermal physics · Further mechanics and thermal physics

Problem

Which of the following expressions gives the work done by an ideal gas when it undergoes a reversible isothermal change from an initial volume

V_i

to a final volume

V_f

at temperature

T

? (Symbols have their usual meaning.) (a)

W = -\,nRT \,\ln\left(\dfrac{V_f}{V_i}\right)

(b)

W = nRT \ln\dfrac{V_f}{V_i}

(c)

W = nRT \left(\dfrac{V_f - V_i}{V_i}\right)

(d)

W = \dfrac{1}{2}\,nR\left( V_f^{\,2} - V_i^{\,2} \right)