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NCERT Solutions › Physics › Chapter 11

Chapter 11: Thermal Properties of Matter

NCERT Solutions for CBSE Class 10 Physics — 105 solved questions with detailed explanations.

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Solved Questions

Q1. The coefficient of linear expansion of a metal rod is 12 × 10⁻⁶ /°C. If the rod is 1 m long at 20°C, its length at 120°C is:

Difficulty: Easy-Medium · Topic: Thermal Expansion

Solution

ΔL = LαΔT = 1 × 12×10⁻⁶ × 100 = 1.2×10⁻³ m. L = 1.0012 m.

Q2. A rod of length 1 m (α=12×10⁻⁶/°C) is heated by 100°C. The new length is:

Difficulty: Easy-Medium · Topic: Thermal Expansion

Solution

ΔL = LαΔT = 1×12×10⁻⁶×100 = 0.0012 m. L = 1.0012 m.

Q3. A rod of length 2 m (α=11×10⁻⁶/°C) is heated by 50°C. The new length is:

Difficulty: Easy-Medium · Topic: Thermal Expansion

Solution

ΔL = LαΔT = 2×11×10⁻⁶×50 = 0.0011 m. L = 2.0011 m.

Q4. A rod of length 0.5 m (α=24×10⁻⁶/°C) is heated by 200°C. The new length is:

Difficulty: Easy-Medium · Topic: Thermal Expansion

Solution

ΔL = LαΔT = 0.5×24×10⁻⁶×200 = 0.0024 m. L = 0.5024 m.

Q5. A rod of length 1 m (α=23×10⁻⁶/°C) is heated by 80°C. The new length is:

Difficulty: Easy-Medium · Topic: Thermal Expansion

Solution

ΔL = LαΔT = 1×23×10⁻⁶×80 = 0.00184 m. L = 1.00184 m.

Q6. A rod of length 3 m (α=12×10⁻⁶/°C) is heated by 60°C. The new length is:

Difficulty: Easy-Medium · Topic: Thermal Expansion

Solution

ΔL = LαΔT = 3×12×10⁻⁶×60 = 0.00216 m. L = 3.00216 m.

Q7. Heat required to raise temperature of 1 kg substance (specific heat 4200 J/kg·K) by 10°C is:

Difficulty: Easy-Medium · Topic: Calorimetry

Solution

Q = msΔT = 1×4200×10 = 42000 J.

Q8. Heat required to raise temperature of 2 kg substance (specific heat 4200 J/kg·K) by 5°C is:

Difficulty: Easy-Medium · Topic: Calorimetry

Solution

Q = msΔT = 2×4200×5 = 42000 J.

Q9. Heat required to raise temperature of 0.5 kg substance (specific heat 900 J/kg·K) by 20°C is:

Difficulty: Easy-Medium · Topic: Calorimetry

Solution

Q = msΔT = 0.5×900×20 = 9000 J.

Q10. Heat required to raise temperature of 1 kg substance (specific heat 390 J/kg·K) by 50°C is:

Difficulty: Easy-Medium · Topic: Calorimetry

Solution

Q = msΔT = 1×390×50 = 19500 J.

Q11. Heat required to raise temperature of 2 kg substance (specific heat 900 J/kg·K) by 30°C is:

Difficulty: Easy-Medium · Topic: Calorimetry

Solution

Q = msΔT = 2×900×30 = 54000 J.

Q12. A metal rod (100 cm, α=10×10⁻⁶/°C) is heated from 20°C to 120°C. Increase in length is:

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL = LαΔT.

Q13. A metal rod (110 cm, α=12×10⁻⁶/°C) is heated from 20°C to 130°C. Increase in length is:

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL = LαΔT.

Q14. A metal rod (120 cm, α=14×10⁻⁶/°C) is heated from 20°C to 140°C. Increase in length is:

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL = LαΔT.

Q15. A metal rod (130 cm, α=16×10⁻⁶/°C) is heated from 20°C to 150°C. Increase in length is:

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL = LαΔT.

Q16. A metal rod (140 cm, α=18×10⁻⁶/°C) is heated from 20°C to 160°C. Increase in length is:

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL = LαΔT.

Q17. A metal rod (150 cm, α=20×10⁻⁶/°C) is heated from 20°C to 170°C. Increase in length is:

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL = LαΔT.

Q18. A metal rod (160 cm, α=22×10⁻⁶/°C) is heated from 20°C to 180°C. Increase in length is:

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL = LαΔT.

Q19. A metal rod (170 cm, α=24×10⁻⁶/°C) is heated from 20°C to 190°C. Increase in length is:

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL = LαΔT.

Q20. A metal rod (180 cm, α=26×10⁻⁶/°C) is heated from 20°C to 200°C. Increase in length is:

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL = LαΔT.

Q21. A metal rod (190 cm, α=28×10⁻⁶/°C) is heated from 20°C to 210°C. Increase in length is:

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL = LαΔT.

Q22. A metal rod (200 cm, α=30×10⁻⁶/°C) is heated from 20°C to 220°C. Increase in length is:

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL = LαΔT.

Q23. A metal rod (210 cm, α=32×10⁻⁶/°C) is heated from 20°C to 230°C. Increase in length is:

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL = LαΔT.

Q24. A metal rod (220 cm, α=34×10⁻⁶/°C) is heated from 20°C to 240°C. Increase in length is:

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL = LαΔT.

Q25. A metal rod (230 cm, α=36×10⁻⁶/°C) is heated from 20°C to 250°C. Increase in length is:

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL = LαΔT.

Q26. A metal rod (240 cm, α=38×10⁻⁶/°C) is heated from 20°C to 260°C. Increase in length is:

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL = LαΔT.

Q27. A metal rod (250 cm, α=40×10⁻⁶/°C) is heated from 20°C to 270°C. Increase in length is:

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL = LαΔT.

Q28. A metal rod (260 cm, α=42×10⁻⁶/°C) is heated from 20°C to 280°C. Increase in length is:

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL = LαΔT.

Q29. A metal rod (270 cm, α=44×10⁻⁶/°C) is heated from 20°C to 290°C. Increase in length is:

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL = LαΔT.

Q30. A metal rod (280 cm, α=46×10⁻⁶/°C) is heated from 20°C to 300°C. Increase in length is:

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL = LαΔT.

Q31. A metal rod (290 cm, α=48×10⁻⁶/°C) is heated from 20°C to 310°C. Increase in length is:

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL = LαΔT.

Q32. Rod L=0.5m, α=10×10⁻⁶/°C, ΔT=10°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=5e-05 m.

Q33. Rod L=0.5m, α=10×10⁻⁶/°C, ΔT=20°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.0001 m.

Q34. Rod L=0.5m, α=10×10⁻⁶/°C, ΔT=50°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00025 m.

Q35. Rod L=0.5m, α=10×10⁻⁶/°C, ΔT=80°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.0004 m.

Q36. Rod L=0.5m, α=10×10⁻⁶/°C, ΔT=100°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.0005 m.

Q37. Rod L=0.5m, α=10×10⁻⁶/°C, ΔT=150°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00075 m.

Q38. Rod L=0.5m, α=10×10⁻⁶/°C, ΔT=200°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.001 m.

Q39. Rod L=0.5m, α=11×10⁻⁶/°C, ΔT=10°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=5.5e-05 m.

Q40. Rod L=0.5m, α=11×10⁻⁶/°C, ΔT=20°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00011 m.

Q41. Rod L=0.5m, α=11×10⁻⁶/°C, ΔT=50°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.000275 m.

Q42. Rod L=0.5m, α=11×10⁻⁶/°C, ΔT=80°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00044 m.

Q43. Rod L=0.5m, α=11×10⁻⁶/°C, ΔT=100°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00055 m.

Q44. Rod L=0.5m, α=11×10⁻⁶/°C, ΔT=150°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.000825 m.

Q45. Rod L=0.5m, α=11×10⁻⁶/°C, ΔT=200°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.0011 m.

Q46. Rod L=0.5m, α=12×10⁻⁶/°C, ΔT=10°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=6e-05 m.

Q47. Rod L=0.5m, α=12×10⁻⁶/°C, ΔT=20°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00012 m.

Q48. Rod L=0.5m, α=12×10⁻⁶/°C, ΔT=50°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.0003 m.

Q49. Rod L=0.5m, α=12×10⁻⁶/°C, ΔT=80°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00048 m.

Q50. Rod L=0.5m, α=12×10⁻⁶/°C, ΔT=100°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.0006 m.

Q51. Rod L=0.5m, α=12×10⁻⁶/°C, ΔT=150°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.0009 m.

Q52. Rod L=0.5m, α=12×10⁻⁶/°C, ΔT=200°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.0012 m.

Q53. Rod L=0.5m, α=17×10⁻⁶/°C, ΔT=10°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=8.5e-05 m.

Q54. Rod L=0.5m, α=17×10⁻⁶/°C, ΔT=20°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00017 m.

Q55. Rod L=0.5m, α=17×10⁻⁶/°C, ΔT=50°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.000425 m.

Q56. Rod L=0.5m, α=17×10⁻⁶/°C, ΔT=80°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00068 m.

Q57. Rod L=0.5m, α=17×10⁻⁶/°C, ΔT=100°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00085 m.

Q58. Rod L=0.5m, α=17×10⁻⁶/°C, ΔT=150°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.001275 m.

Q59. Rod L=0.5m, α=17×10⁻⁶/°C, ΔT=200°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.0017 m.

Q60. Rod L=0.5m, α=23×10⁻⁶/°C, ΔT=10°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.000115 m.

Q61. Rod L=0.5m, α=23×10⁻⁶/°C, ΔT=20°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00023 m.

Q62. Rod L=0.5m, α=23×10⁻⁶/°C, ΔT=50°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.000575 m.

Q63. Rod L=0.5m, α=23×10⁻⁶/°C, ΔT=80°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00092 m.

Q64. Rod L=0.5m, α=23×10⁻⁶/°C, ΔT=100°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00115 m.

Q65. Rod L=0.5m, α=23×10⁻⁶/°C, ΔT=150°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.001725 m.

Q66. Rod L=0.5m, α=23×10⁻⁶/°C, ΔT=200°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.0023 m.

Q67. Rod L=0.5m, α=24×10⁻⁶/°C, ΔT=10°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00012 m.

Q68. Rod L=0.5m, α=24×10⁻⁶/°C, ΔT=20°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00024 m.

Q69. Rod L=0.5m, α=24×10⁻⁶/°C, ΔT=50°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.0006 m.

Q70. Rod L=0.5m, α=24×10⁻⁶/°C, ΔT=80°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00096 m.

Q71. Rod L=0.5m, α=24×10⁻⁶/°C, ΔT=100°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.0012 m.

Q72. Rod L=0.5m, α=24×10⁻⁶/°C, ΔT=150°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.0018 m.

Q73. Rod L=0.5m, α=24×10⁻⁶/°C, ΔT=200°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.0024 m.

Q74. Rod L=1m, α=10×10⁻⁶/°C, ΔT=10°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.0001 m.

Q75. Rod L=1m, α=10×10⁻⁶/°C, ΔT=20°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.0002 m.

Q76. Rod L=1m, α=10×10⁻⁶/°C, ΔT=50°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.0005 m.

Q77. Rod L=1m, α=10×10⁻⁶/°C, ΔT=80°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.0008 m.

Q78. Rod L=1m, α=10×10⁻⁶/°C, ΔT=100°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.001 m.

Q79. Rod L=1m, α=10×10⁻⁶/°C, ΔT=150°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.0015 m.

Q80. Rod L=1m, α=10×10⁻⁶/°C, ΔT=200°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.002 m.

Q81. Rod L=1m, α=11×10⁻⁶/°C, ΔT=10°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00011 m.

Q82. Rod L=1m, α=11×10⁻⁶/°C, ΔT=20°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00022 m.

Q83. Rod L=1m, α=11×10⁻⁶/°C, ΔT=50°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00055 m.

Q84. Rod L=1m, α=11×10⁻⁶/°C, ΔT=80°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00088 m.

Q85. Rod L=1m, α=11×10⁻⁶/°C, ΔT=100°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.0011 m.

Q86. Rod L=1m, α=11×10⁻⁶/°C, ΔT=150°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00165 m.

Q87. Rod L=1m, α=11×10⁻⁶/°C, ΔT=200°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.0022 m.

Q88. Rod L=1m, α=12×10⁻⁶/°C, ΔT=10°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00012 m.

Q89. Rod L=1m, α=12×10⁻⁶/°C, ΔT=20°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00024 m.

Q90. Rod L=1m, α=12×10⁻⁶/°C, ΔT=50°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.0006 m.

Q91. Rod L=1m, α=12×10⁻⁶/°C, ΔT=80°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00096 m.

Q92. Rod L=1m, α=12×10⁻⁶/°C, ΔT=100°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.0012 m.

Q93. Rod L=1m, α=12×10⁻⁶/°C, ΔT=150°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.0018 m.

Q94. Rod L=1m, α=12×10⁻⁶/°C, ΔT=200°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.0024 m.

Q95. Rod L=1m, α=17×10⁻⁶/°C, ΔT=10°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00017 m.

Q96. Rod L=1m, α=17×10⁻⁶/°C, ΔT=20°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00034 m.

Q97. Rod L=1m, α=17×10⁻⁶/°C, ΔT=50°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00085 m.

Q98. Rod L=1m, α=17×10⁻⁶/°C, ΔT=80°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00136 m.

Q99. Rod L=1m, α=17×10⁻⁶/°C, ΔT=100°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.0017 m.

Q100. Rod L=1m, α=17×10⁻⁶/°C, ΔT=150°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00255 m.

Q101. Rod L=1m, α=17×10⁻⁶/°C, ΔT=200°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.0034 m.

Q102. Rod L=1m, α=23×10⁻⁶/°C, ΔT=10°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00023 m.

Q103. Rod L=1m, α=23×10⁻⁶/°C, ΔT=20°C. ΔL=

Difficulty: Easy-Medium · Topic: Expansion

Solution

ΔL=LαΔT=0.00046 m.

Q104. Two rods of same length and area but materials of thermal conductivities K₁ and K₂ are connected in series. The effective thermal conductivity is:

Difficulty: Medium · Topic: Thermal Conductivity

Solution

For series: L_total/K_eff = L₁/K₁ + L₂/K₂. For equal lengths: 2/K_eff = 1/K₁ + 1/K₂. K_eff = 2K₁K₂/(K₁+K₂).

Q105. A body cools from 80°C to 60°C in 10 minutes. The surrounding temperature is 20°C. By Newton's law of cooling, the time to cool from 60°C to 40°C is approximately:

Difficulty: Medium · Topic: Newton's Cooling

Solution

Rate ∝ (T_avg - T_surr). First case: avg = 70, excess = 50. Second: avg = 50, excess = 30. Time = 10 × 50/30 ≈ 16.67 min ≈ 15 min (closest).

Other Chapters in Physics

Ch 1: Physical WorldCh 2: Units & MeasurementsCh 3: Motion in a Straight LineCh 4: Motion in a PlaneCh 5: Laws of MotionCh 6: Work Energy & PowerCh 7: System of ParticlesCh 8: GravitationCh 9: Mechanical Properties of SolidsCh 10: Mechanical Properties of FluidsCh 12: ThermodynamicsCh 13: Kinetic TheoryCh 14: OscillationsCh 15: Waves

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