Class 11 · Chapter 11
Overview, notes, short notes, formula sheet, daily practice problems, previous year questions, and videos for this chapter — all in one place.
9 formulas across 3 topics in Thermal Properties of Matter.
Updated 2026-07-04 · v1.0.0
Temperature scales are linear maps of each other; expansion coefficients are linked by the simple chain α : β : γ = 1 : 2 : 3.
C/5 = (F − 32)/9 = (K − 273.15)/5
| Symbol | Meaning | Unit | Dimension |
|---|---|---|---|
| C, F, K | temperature in Celsius, Fahrenheit, Kelvin | °C, °F, K | [Θ] |
Valid when
Common mistakes
ΔL = L α ΔT; α : β : γ = 1 : 2 : 3
| Symbol | Meaning | Unit | Dimension |
|---|---|---|---|
| α | coefficient of linear expansion | K⁻¹ (or °C⁻¹) | [Θ⁻¹] |
| β | areal coefficient (= 2α) | K⁻¹ | [Θ⁻¹] |
| γ | volumetric coefficient (= 3α) | K⁻¹ | [Θ⁻¹] |
| ΔT | temperature change | K (or °C) | [Θ] |
Valid when
Common mistakes
ΔT/T = ½ α Δθ (fractional time change of a pendulum clock)
T ∝ √L with ΔL/L = αΔθ, then binomial approximation
| Symbol | Meaning | Unit | Dimension |
|---|---|---|---|
| ΔT/T | fractional change in the period | dimensionless | [M⁰L⁰T⁰] |
| Δθ | rise in temperature | K (or °C) | [Θ] |
Valid when
Worth remembering
Heat either raises temperature (mcΔT) or changes phase (mL) — never both at once. Mixture problems are pure bookkeeping of these two.
Q = m c ΔT
| Symbol | Meaning | Unit | Dimension |
|---|---|---|---|
| Q | heat supplied | J | [ML²T⁻²] |
| c | specific heat capacitywater: 4186 J/(kg·K) ≈ 1 cal/(g·°C) | J/(kg·K) | [L²T⁻²Θ⁻¹] |
| ΔT | temperature change | K (or °C) | [Θ] |
Valid when
Common mistakes
Q = m L
| Symbol | Meaning | Unit | Dimension |
|---|---|---|---|
| L | latent heat of fusion/vaporisationice: 3.34 × 10⁵ J/kg; steam: 22.6 × 10⁵ J/kg | J/kg | [L²T⁻²] |
Valid when
Common mistakes
Worth remembering
Conduction is Ohm's law with temperature in place of voltage; radiation follows Stefan's T⁴ law; Newton's cooling is its small-difference limit.
H = dQ/dt = kA(T₁ − T₂)/L
| Symbol | Meaning | Unit | Dimension |
|---|---|---|---|
| H | heat current | W | [ML²T⁻³] |
| k | thermal conductivity of the material | W/(m·K) | [MLT⁻³Θ⁻¹] |
| A | cross-sectional area | m² | [L²] |
| L | length of the conductor | m | [L] |
Valid when
Common mistakes
P = σ A e T⁴; net loss: P = σAe(T⁴ − T₀⁴)
| Symbol | Meaning | Unit | Dimension |
|---|---|---|---|
| σ | Stefan-Boltzmann constantσ = 5.67 × 10⁻⁸ W/(m²·K⁴) | W/(m²·K⁴) | [MT⁻³Θ⁻⁴] |
| e | emissivity (1 for a perfect black body) | dimensionless | [M⁰L⁰T⁰] |
| T | absolute temperature of the surface | K | [Θ] |
| T₀ | temperature of the surroundings | K | [Θ] |
Valid when
Common mistakes
λ(max) T = b
| Symbol | Meaning | Unit | Dimension |
|---|---|---|---|
| λ(max) | wavelength of peak emission | m | [L] |
| b | Wien's constantb = 2.9 × 10⁻³ m·K | m·K | [LΘ] |
Valid when
Common mistakes
dT/dt = −K(T − T₀)
Stefan's law linearised for small (T − T₀)
| Symbol | Meaning | Unit | Dimension |
|---|---|---|---|
| T | body temperature at time t | K (or °C) | [Θ] |
| T₀ | surrounding temperature | K (or °C) | [Θ] |
| K | cooling constant (setup-dependent) | s⁻¹ | [T⁻¹] |
Valid when
Common mistakes
Worth remembering
NEET rotates Stefan-ratio and Newton's-cooling interval questions yearly; JEE builds composite-slab conduction ladders — solve them as resistor networks.
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