Question

Based on the first law of thermodynamics, which one of the following is correct ?

• A. $\text{For an isochoric process, E = -Q}$
• B. $\text{For an adiabatic process, E = -Q}$
• C. $\text{For an isothermal process, E = -Q}$
• D. $\text{For an cyclic process, W = -Q}$

Answer 1

Answer: (D)

$\text{For an cyclic process, W = -Q}$

When a system returns to its original state after completing a series of changes, then it is known that a cycle is completed. This process is known as cyclic process. In a cyclic process the initial and the final state is same. As the internal energy U of the system depends only on the state of the system so in a cyclic process the net change of internal energy, ∆U will be equal to zero i.e. ∆U = 0. Hence from the first law (∆U = Q+W)

Hence, W = – Q