Verified Solution • 2025–26 Session moderate

QPages 98-102: Q16: HC Verma: Concepts of Physics - Volume 2 Heat Transfer Pages 98-102: Q16 Solution: Three rods of lengths 20 cm each and area of cross section are…

⚠️ Common Exam Traps & Conceptual Pitfalls

Students often attempt to calculate heat flow through rod BC by assuming it must conduct heat due to the network configuration, but since $T_B = T_C = 80^circ ext{C}$, the temperature gradient $Delta T$ is zero, resulting in zero heat flow regardless of the rod's high conductivity.

Three rods of lengths 20 cm each and area of cross section 1 cm21 \text{ cm}^2 are joined to form a triangle ABC. The conductivities of the rods are KAB=50 J s−1 m−1 �C−1K_{AB} = 50 \text{ J s}^{-1} \text{ m}^{-1} \text{ �C}^{-1}, KBC=200 J s−1 m−1 �C−1K_{BC} = 200 \text{ J s}^{-1} \text{ m}^{-1} \text{ �C}^{-1} and KAC=400 J s−1 m−1 �C−1K_{AC} = 400 \text{ J s}^{-1} \text{ m}^{-1} \text{ �C}^{-1}. The junctions A, B and C are maintained at 40�C, 80�C and 80�C respectively. Find the rate of heat flowing through the rods AB, AC and BC.

Step-by-Step Verified Solution

**Answer:** Heat flow through AB = 1 W, AC = 8 W, BC = 0. **Step-by-Step Explanation:** Given: l = 20 cm = 0.2 m, A = 1 cm_ = 10__ m_, T_A = 40�C, T_B = 80�C, T_C = 80�C. K_AB = 50, K_BC = 200, K_AC = 400.
ΔQABΔt=50×10−4×(80−40)0.2=1 W\frac{\Delta Q_{AB}}{\Delta t} = \frac{50 \times 10^{-4} \times (80-40)}{0.2} = 1 \text{ W}
ΔQACΔt=400×10−4×(80−40)0.2=8 W\frac{\Delta Q_{AC}}{\Delta t} = \frac{400 \times 10^{-4} \times (80-40)}{0.2} = 8 \text{ W}
ΔQBCΔt=200×10−4×(80−80)0.2=0\frac{\Delta Q_{BC}}{\Delta t} = \frac{200 \times 10^{-4} \times (80-80)}{0.2} = 0
[citation:14]

All Questions in this Chapter

QPage 97: Q1 QPage 97: Q2 QPage 97: Q3 QPage 97: Q4 QPage 97: Q5 QPage 97: Q6 QPage 97: Q7 QPage 97: Q8 QPage 97: Q9 QPage 97: Q10 QPages 96-97: Q1 QPages 96-97: Q2 QPages 96-97: Q3 QPages 96-97: Q4 QPages 96-97: Q5 QPages 96-97: Q6 QPages 96-97: Q7 QPages 96-97: Q8 QPages 96-97: Q9 QPages 96-97: Q10 QPages 96-97: Q11 QPages 97-98: Q1 QPages 97-98: Q2 QPages 97-98: Q3 QPages 97-98: Q4 QPages 97-98: Q5 QPages 97-98: Q6 QPages 98-102: Q1 QPages 98-102: Q2 QPages 98-102: Q3 QPages 98-102: Q4 QPages 98-102: Q5 QPages 98-102: Q6 QPages 98-102: Q7 QPages 98-102: Q8 QPages 98-102: Q9 QPages 98-102: Q10 QPages 98-102: Q11 QPages 98-102: Q12 QPages 98-102: Q13 QPages 98-102: Q14 QPages 98-102: Q15 QPages 98-102: Q16 QPages 98-102: Q17 QPages 98-102: Q18 QPages 98-102: Q19 QPages 98-102: Q20 QPages 98-102: Q21 QPages 98-102: Q22 QPages 98-102: Q23 QPages 98-102: Q24 QPages 98-102: Q25 QPages 98-102: Q26 QPages 98-102: Q27 QPages 98-102: Q28 QPages 98-102: Q29 QPages 98-102: Q30 QPages 98-102: Q31 QPages 98-102: Q32 QPages 98-102: Q33 QPages 98-102: Q34 QPages 98-102: Q35 QPages 98-102: Q36 QPages 98-102: Q37 QPages 98-102: Q38 QPages 98-102: Q39 QPages 98-102: Q40 QPages 98-102: Q41 QPages 98-102: Q42 QPages 98-102: Q43 QPages 98-102: Q44 QPages 98-102: Q45 QPages 98-102: Q46 QPages 98-102: Q47 QPages 98-102: Q48 QPages 98-102: Q49 QPages 98-102: Q50 QPages 98-102: Q51 QPages 98-102: Q52 QPages 98-102: Q53 QPages 98-102: Q54 QPages 98-102: Q55

Related Learning Resources & Exam Preparation

Chapter Practice Bank
Practice all topic-wise questions from Heat Transfer
Reference Textbook Solutions
Explore complete chapter exercises for HC Verma: Concepts of Physics - Volume 2
Competitive PYQ Question Bank
Browse year-wise authentic previous years' questions with solutions
Authentic CBT Mock Tests
Simulate official exam environment with live timer and percentile scoring