Thermal Physics

Physics, SSC-Punjab Class 10. This chapter is split into 43 topics and has 1,014 practice questions. The topics covered are listed below, followed by 10 free sample questions from the chapter.

Topics in this chapter

1. Coefficients of linear expansion of materials 22 questions
2. Evaporation: meaning and particle explanation 21 questions
3. Effects of the large specific heat capacity of water 20 questions
4. Consequences of expansion: railways, bridges, jars and pipes 23 questions
5. Numericals: heat required Q = mcΔT 25 questions
6. Melting points, boiling points and latent heats of common substances 25 questions
7. Exercise-style questions on expansion and specific heat 21 questions
8. Specific heat capacity: definition, formula and units 24 questions
9. Numericals: latent heat of fusion Q = mL 25 questions
10. Change of state and the particle model 24 questions
11. Thermal expansion and contraction 24 questions
12. Superconductivity: meaning and materials 23 questions
13. Numericals: finding the temperature change 25 questions
14. Specific heat capacity of solids and liquids 22 questions
15. Refrigeration without CFCs 23 questions
16. Numericals: finding mass and specific heat capacity 25 questions
17. Linear expansion law and formula 23 questions
18. Latent heat: meaning and particle explanation 24 questions
19. Uses of superconductors 24 questions
20. Numericals: temperature change and final temperature 25 questions
21. Factors affecting evaporation 23 questions
22. Numericals: original length and combined expansion problems 25 questions
23. Numericals: finding the coefficient of linear expansion 25 questions
24. Numericals: increase in length of a heated solid 25 questions
25. Thermal expansion of liquids: real and apparent expansion 24 questions
26. Numericals: coefficient of volume expansion and temperature rise 25 questions
27. Cooling caused by evaporation and sweating 22 questions
28. Numericals: heat for several stages of heating and change of state 25 questions
29. Numericals: increase in volume on heating 25 questions
30. Gas pressure and the motion of particles 23 questions
31. Thermal expansion of gases and Charles' law 23 questions
32. Numericals: heating with an electric heater 25 questions
33. Reasoning with ratios in thermal physics problems 22 questions
34. Numericals: real and apparent expansion of liquids 25 questions
35. Numericals: final length after heating 25 questions
36. Numericals: final volume of a heated substance 25 questions
37. Expansion: reasoning, brain teasers and misconceptions 23 questions
38. Car engine cooling system using water 21 questions
39. Volume expansion of solids 23 questions
40. Consequences of expansion: thermometers, wires and everyday life 22 questions
41. Numericals: latent heat of vaporization Q = mL 25 questions
42. Latent heat of fusion and latent heat of vaporization 22 questions
43. Temperature-time graph on heating ice and experiments 23 questions

Sample questions: Thermal Physics

10 sample questions with the correct answer and an explanation. Try to answer each one before reading the explanation.

Q1. Which of these expands by the same amount as a steel rod of equal length for the same temperature rise?

• A. Concrete, as both have &alpha(correct answer)
• B. A gold rod, since both of them are dense
• C. A tungsten rod, since both are very hard
• D. A silver rod, since both of them are shiny

Answer: A.Equal α gives equal expansion for equal original length and ΔT; steel and concrete share 1.2 × 10⁻⁵ K⁻¹. Matching concrete and steel is also why reinforced concrete does not crack.

Q2. The coefficient of linear expansion of aluminium is 2.4 × 10⁻⁵ K⁻¹. Find the increase in length of a 1.5 m aluminium bar when its temperature rises from 25 °C to 125 °C.

• A. 3.6 mm(correct answer)
• B. 36 mm
• C. 1.504 m
• D. 0.36 mm

Answer: A.ΔL = α L₀ ΔT = 2.4 × 10⁻⁵ × 1.5 × 100 = 3.6 mm. (Using the final temperature instead of ΔT, or slipping a power of ten, gives the wrong values.)

Q3. What is ΔL for a brass wire of original length 0.8 m heated through 200 K, if α = 1.9 × 10⁻⁵ K⁻¹?

• A. 3.27 mm
• B. 3.04 mm(correct answer)
• C. 30.4 mm
• D. 0.803 m

Answer: B.ΔL = α L₀ ΔT = 1.9 × 10⁻⁵ × 0.8 × 200 = 3.04 mm. (Using the final temperature instead of ΔT, or slipping a power of ten, gives the wrong values.)

Q4. What is ΔL for a copper wire of original length 2.5 m heated through 200 K, if α = 1.7 × 10⁻⁵ K⁻¹?

• A. 9.35 mm
• B. 85 mm
• C. 2.509 m
• D. 8.5 mm(correct answer)

Answer: D.ΔL = α L₀ ΔT = 1.7 × 10⁻⁵ × 2.5 × 200 = 8.5 mm. (Using the final temperature instead of ΔT, or slipping a power of ten, gives the wrong values.)

Q5. A silver rod is 1.2 m long at 20 °C. By how much does it lengthen when heated to 80 °C? (α = 1.93 × 10⁻⁵ K⁻¹)

• A. 13.9 mm
• B. 1.39 mm(correct answer)
• C. 0.139 mm
• D. 1.85 mm

Answer: B.ΔL = α L₀ ΔT = 1.93 × 10⁻⁵ × 1.2 × 60 = 1.39 mm. (Using the final temperature instead of ΔT, or slipping a power of ten, gives the wrong values.)

Q6. The coefficient of linear expansion of gold is 1.3 × 10⁻⁵ K⁻¹. Find the increase in length of a 0.5 m gold bar when its temperature rises from 25 °C to 325 °C.

• A. 1.95 mm(correct answer)
• B. 19.5 mm
• C. 0.195 mm
• D. 0.502 m

Answer: A.ΔL = α L₀ ΔT = 1.3 × 10⁻⁵ × 0.5 × 300 = 1.95 mm. (Using the final temperature instead of ΔT, or slipping a power of ten, gives the wrong values.)

Q7. What is ΔL for a Pyrex glass wire of original length 0.25 m heated through 300 K, if α = 0.4 × 10⁻⁵ K⁻¹?

• A. 0.32 mm
• B. 250 mm
• C. 0.3 mm(correct answer)
• D. 3 mm

Answer: C.ΔL = α L₀ ΔT = 0.4 × 10⁻⁵ × 0.25 × 300 = 0.3 mm. (Using the final temperature instead of ΔT, or slipping a power of ten, gives the wrong values.)

Q8. What is ΔL for a copper wire of original length 0.6 m heated through 100 K, if α = 1.7 × 10⁻⁵ K⁻¹?

• A. 1.02 mm(correct answer)
• B. 0.601 m
• C. 10.2 mm
• D. 0.102 mm

Answer: A.ΔL = α L₀ ΔT = 1.7 × 10⁻⁵ × 0.6 × 100 = 1.02 mm. (Using the final temperature instead of ΔT, or slipping a power of ten, gives the wrong values.)

Q9. A ordinary glass rod is 1.5 m long at 20 °C. By how much does it lengthen when heated to 120 °C? (α = 0.9 × 10⁻⁵ K⁻¹)

• A. 1.62 mm
• B. 0.135 mm
• C. 13.5 mm
• D. 1.35 mm(correct answer)

Answer: D.ΔL = α L₀ ΔT = 0.9 × 10⁻⁵ × 1.5 × 100 = 1.35 mm. (Using the final temperature instead of ΔT, or slipping a power of ten, gives the wrong values.)

Q10. A liquid and its glass flask have the same coefficient of volume expansion. What apparent expansion is observed when they are heated together?

• A. Twice the real expansion
• B. Cannot be said at all
• C. Zero(correct answer)
• D. Equal to the real expansion

Answer: C.Real = apparent + container; if container expansion equals the liquid's real expansion, the apparent expansion is zero (the level does not change).