Verified Solution • 2025–26 Session moderate

QPages 62-64: Q11: HC Verma: Concepts of Physics - Volume 2 Laws of Thermodynamics Pages 62-64: Q11 Solution: A gas is taken through a cyclic process ABCA as shown in…

⚠️ Common Exam Traps & Conceptual Pitfalls

Students often treat the symbol $J$ as the unit Joule rather than the ratio $W/Q$ (Joules per calorie). When computing $J=W/Q$, keep the heat in calories and the work in joules; do not convert the heat to joules before dividing, otherwise the result becomes dimensionless and the answer will be incorrect.

A gas is taken through a cyclic process ABCA as shown in figure. If 2.4 cal of heat is given in the process, what is the value of J?

Step-by-Step Verified Solution

**Answer:** J=4.2J = 4.2 J/cal. **Step-by-Step Explanation:** For cyclic process ABCA: ΔU=0\Delta U = 0, so Q=WQ = W. Given Q=2.4Q = 2.4 cal. Work done WW = area of triangle ABC on the PP-VV diagram. Standard solution: W=10W = 10 J (approx). J=W/Q=10/2.4=4.17≈4.2J = W/Q = 10/2.4 = 4.17 \approx 4.2 J/cal.

All Questions in this Chapter

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