Schooling · Class 11 · Physics · Thermal Properties of Matter · Chapter on a page
CBSE Class 11 · Physics · NCERT Physics Part-II
Thermal Properties of Matter: chapter on a page
A cut of Shishya's notes for this chapter: the first paragraph of the introduction and the key ideas, formulas and facts, common mistakes and quick revision lists, word for word. Nothing is added or reworded; the worked examples are left out (they are on the chapter page).
About the notes: Written by Shishya's AI on 27 Sept 2026 from the chapter's title and class level, in Shishya's own words — not a copy or summary of the textbook. Read the official chapter for the book's own text, activities and exercises.
Fact-checked on 21 Oct 2026: an AI-assisted check of this note against cited sources; the errors it found were corrected that day. Some errors may remain.
Mind map
Drawn from the same notes by a fixed rule (no AI): each label is the item's own words — its bold term, its label before a colon, a short formula as written, or its first words.
The mind map as a list
- Key ideas
- Temperature
- Heat
- Thermal equilibrium
- Linear, area and volume expansion
- Specific heat capacity (c)
- Latent heat (L)
- Conduction
- Formulas and facts
- T(K) = T(°C) + 273.15
- T(°F) = (9/5)T(°C) + 32
- ΔL = αL₀ΔT
- ΔV = γV₀ΔT, γ ≈ 3α
- Q = mcΔT
- Q = mL
- H = kA(T₁ − T₂)/d
- Worked examples
- Temperature conversion
- Thermal expansion of a steel rod
- Calorimetry (heat exchange)
- Watch out for
- Using Celsius instead of Kelvin in…
- Forgetting that γ ≈ 3α for volume…
- Confusing heat and temperature…
- Ignoring sign conventions in…
- Assuming latent heat causes a…
What this chapter is about
This chapter explores how matter responds to changes in temperature. You will study the concepts of heat and temperature, learn how to measure temperature using different scales, and understand the various ways heat transfers from one body to another. The chapter builds on your earlier understanding of energy and introduces thermal expansion, specific heat capacity, latent heat, and the three modes of heat transfer: conduction, convection and radiation.
Key ideas
- Temperature is a measure of the average kinetic energy of molecules in a substance; it determines the direction of heat flow between two bodies in contact.
- Heat is energy transferred between bodies due to a temperature difference; SI unit is joule (J), though calorie (cal) is sometimes used (1 cal = 4.186 J).
- Thermal equilibrium occurs when two bodies in contact reach the same temperature and no net heat flows between them (zeroth law of thermodynamics).
- Linear, area and volume expansion: when temperature rises by ΔT, a solid's length changes by ΔL = αL₀ΔT, area by ΔA = βA₀ΔT (β ≈ 2α), and volume by ΔV = γV₀ΔT (γ ≈ 3α), where α, β, γ are expansion coefficients.
- Specific heat capacity (c): heat needed to raise 1 kg of a substance by 1 K; Q = mcΔT.
- Latent heat (L): heat needed to change the phase of 1 kg of a substance without temperature change; Q = mL.
- Conduction transfers heat through a material without bulk motion; rate depends on thermal conductivity, area, temperature gradient and thickness.
- Convection transfers heat by bulk movement of fluid; radiation transfers heat through electromagnetic waves and needs no medium.
Formulas and facts to remember
- Formula: T(K) = T(°C) + 273.15 · Meaning: Conversion from Celsius to Kelvin
- Formula: T(°F) = (9/5)T(°C) + 32 · Meaning: Conversion from Celsius to Fahrenheit
- Formula: ΔL = αL₀ΔT · Meaning: Linear expansion of a solid
- Formula: ΔV = γV₀ΔT, γ ≈ 3α · Meaning: Volume expansion; γ is about three times α
- Formula: Q = mcΔT · Meaning: Heat absorbed or released during temperature change
- Formula: Q = mL · Meaning: Heat absorbed or released during phase change
- Formula: H = kA(T₁ − T₂)/d · Meaning: Rate of heat conduction through a slab (Fourier's law)
- Formula: P = σAT⁴ · Meaning: Power radiated by a black body (Stefan–Boltzmann law); σ = 5.67 × 10⁻⁸ W m⁻² K⁻⁴
- Water has an unusually high specific heat capacity (about 4186 J kg⁻¹ K⁻¹), which moderates climate near coasts.
- Anomalous expansion of water: water is densest at 4 °C, so lakes freeze from the top down and aquatic life survives in winter.
- Good conductors (metals) have high k; insulators (wood, air, wool) have low k.
Common mistakes
- Using Celsius instead of Kelvin in formulas like Stefan–Boltzmann law → Always convert to Kelvin when the formula involves absolute temperature or T⁴.
- Forgetting that γ ≈ 3α for volume expansion of solids → Remember the relation; do not use α directly for volume problems.
- Confusing heat and temperature, treating them as the same quantity → Heat is energy transferred; temperature is a state variable that determines the direction of transfer.
- Ignoring sign conventions in calorimetry (adding heat lost and gained directly) → Set heat lost by hot body equal to heat gained by cold body, keeping magnitudes positive.
- Assuming latent heat causes a temperature change → During phase change, temperature stays constant even though heat is absorbed or released.
Quick revision
- Temperature scales: K = °C + 273; °F = (9/5)°C + 32.
- Linear expansion: ΔL = αL₀ΔT; for volume, use γ ≈ 3α.
- Heat exchange: Q = mcΔT (temperature change) or Q = mL (phase change).
- Conduction rate: H = kAΔT/d; metals conduct well, air and wool insulate.
- Stefan–Boltzmann law for radiation: P = σAT⁴ (T in kelvin).
- Water is densest at 4 °C; this anomalous expansion lets aquatic life survive freezing winters.