Prepare for the Punjab Board Matric Annual Examinations 2027 with Class 10 Physics Chapter 10: Thermal Physics – Class Test 1. This is a Board Standard Full Unit Test, specially designed to help students assess their understanding of Thermal Physics according to the latest Class 10 Physics New Syllabus issued by PECTAA Punjab. As part of our comprehensive Chapter-Wise Test Series, this practice paper supports effective exam preparation, concept revision, and self-assessment. Students can use this test to strengthen their knowledge of thermal physics and prepare confidently for the Punjab Boards 2027 examinations.
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Chapter Wise Class Test
T-1
Chapter-10
Thermal Physics
1.1 Choose the correct Answer.(Time: 7 Minutes)(Total Marks: 7)
1.
If two rods of same length but different materials are heated equally, the rod that expands more has:
(a) Lower α(b) Higher density(c) Higher α(d) Lower temperature
Ans: (c) The expansion is ΔL = αL0ΔT, so the rod with the higher coefficient of linear expansion (α) expands more.
2.
If no space is left in railway tracks, they will:
(a) Shrink(b) Break(c) Melt(d) Buckle
Ans: (d) In hot weather the rails expand; with no gap they bend sideways (buckle).
3.
If two substances receive equal heat and one shows smaller temperature rise, it has:
(a) Lower mass(b) Lower specific heat(c) Higher specific heat(d) Higher density
Ans: (c) Q = mcΔT; for the same Q, a smaller ΔT means a higher specific heat (c).
4.
Metal feels colder than wood because:
(a) Metal is colder(b) Wood produces heat(c) Metal conducts heat away from our hand(d) Wood has lower temperature
Ans: (c) Metal is a good conductor, so it quickly takes heat away from the hand.
5.
When the temperature of a rod of copper is increased, its length:
(a) remains the same(b) increases(c) decreases(d) becomes double
Ans: (b) Solids expand on heating, so the length increases.
6.
The amount by which unit length of a material increases when the temperature is raised to 1°C, is called the coefficient of:
(a) cubic expansion(b) volume expansion(c) linear expansion(d) none of these
Ans: (c) This is the definition of the coefficient of linear expansion (α).
7.
What does a liquid turn into once it is evaporated?
(a) Gas(b) Water vapours(c) Air(d) Both (a) and (b)
Ans: (d) An evaporated liquid becomes gas (vapour); water becomes water vapour.
Class 10 Physics | Chapter-10: Thermal Physics | Objective Type
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Chapter Wise Class Test
T-1
Chapter-10
Thermal Physics
Total Marks: 23(Subjective Type)Time: 33 Minutes
2.Write short answers to any Seven (7) questions.[7 × 2 = 14]
(i)
Why do bridges have expansion joints?
Bridges are made of steel and concrete, which expand in hot weather and contract in cold weather. Expansion joints leave gaps so the material can expand freely, which prevents cracking and buckling.
(ii)
Why does a metal lid open easily when heated?
When heated, the metal lid expands more than the glass jar because metals have a larger coefficient of expansion. The lid becomes loose and opens easily.
(iii)
Why is water used in automobile cooling systems?
Water has a high specific heat capacity (4200 J kg−1 K−1), so it absorbs a large amount of heat from the engine with only a small rise in temperature. It is also cheap and easily available.
(iv)
Why does soil heat up faster than water?
Soil has a lower specific heat than water. For the same amount of heat, the temperature of soil rises more than that of water, so soil heats up faster.
(v)
Why does metal feel colder than wood when touched, if they are both at the same temperature?
Metal is a good conductor of heat, so it quickly takes heat away from our hand and we feel cold. Wood is a poor conductor, so it takes away heat slowly and feels warmer.
(vi)
What is latent heat of fusion?
The heat energy required to change 1 kg of a solid into a liquid at its melting point, without any change in temperature, is called latent heat of fusion. Lf = Q / m (for ice, 3.36 × 105 J/kg).
(vii)
How do different materials exhibit varying thermal expansion behaviours?
Each material has its own coefficient of linear expansion (α), so the change in length ΔL = αL0ΔT is different for the same rise in temperature. For example, aluminium expands more than steel, and glass expands very little. This is used in a bimetallic strip.
(viii)
How does evaporation contribute to cooling processes in everyday life?
During evaporation, the fastest (most energetic) molecules escape from the liquid surface, so the average energy of the remaining liquid falls and it cools. Examples: sweating cools the body, water in an earthen pot stays cool, and wet cloth on the forehead reduces fever.
(ix)
What is latent heat of vaporization, and how is it calculated?
The heat energy required to change 1 kg of a liquid into vapour at its boiling point, without any change in temperature, is called latent heat of vaporization. Lv = Q / m, or Q = mLv. For water, Lv = 2.26 × 106 J/kg.
3.Give Answers of the following questions.[4 + 5 = 9]
(i)
What are some practical consequences of thermal expansion in everyday life, such as in construction materials or household appliances?
- Railway tracks: gaps are left between rails so they do not buckle in summer.
- Bridges and concrete roads: expansion joints allow free expansion and contraction.
- Power lines: cables are hung slightly loose; they sag in summer and tighten in winter.
- Appliances: a bimetallic strip in an electric iron, toaster or thermostat bends on heating and switches the circuit off.
- Glass: a thick glass cracks if heated suddenly because it expands unevenly; metal lids are loosened by warming.
(ii)
A container holds 1 litre of water at 20°C. What will be its volume at 80°C, assuming water’s coefficient of volume expansion is 2.1×10−4 per °C?
Given: V0 = 1 L, T1 = 20°C, T2 = 80°C, β = 2.1 × 10−4 °C−1
ΔT = 80 − 20 = 60°C
ΔV = βV0ΔT = 2.1 × 10−4 × 1 × 60 = 0.0126 L
V = V0 + ΔV = 1 + 0.0126 = 1.0126 L (≈ 1012.6 cm3)
ΔT = 80 − 20 = 60°C
ΔV = βV0ΔT = 2.1 × 10−4 × 1 × 60 = 0.0126 L
V = V0 + ΔV = 1 + 0.0126 = 1.0126 L (≈ 1012.6 cm3)
Class 10 Physics | Chapter-10: Thermal Physics | Subjective Type
