By going through these CBSE Class 11 Physics Notes Chapter 11 Thermal Properties of Matter, students can recall all the concepts quickly.

Thermal Properties of Matter Notes Class 11 Physics Chapter 11

→ Heat is the thermal energy that transfers from a body at a higher temperature to the other body at a lower temperature.

→ Temperature is the property of a body that determines whether or not it is in thermal equilibrium with its surroundings.

→ Thermometry is the branch of heat that deals with the measurement of temperature.

→ S.I. Unit of coefficient of thermal expansion in K-1.

→ The volume of water decreases with the increase in temperature from 0°C to 4°C. It is called the anomalous expansion of water.

→ The density of water is maximum at 4°C and. its maximum value is 1 g cm-3 or 103 kg m-3.

→ Water (0° to 4°C) and silver iodide (80°C to 141°C) contract on heating.

→ Quartz, pyrex glass, fused silica and invar neither expand nor contract on heating.

→ On a freezing, the volume of ice becomes more than that of water in cold countries when the temperature goes below 0°C and thus the pipe expands and may burst.

→ The principle of Calorimetry is:
Heat gained = Heat lost.

→ A sensitive thermometer is one that shows a large change in the position of mercury meniscus for a small change in temperature.

→ The critical temperature is that temperature up to which gas can be liquified by applying pressure alone.

→ Vapour is a gas above the critical temperature and gas is a vapour below the critical temperature.

→ ΔC = ΔK.

→ In order to convert the temperature from one scale to another, the following relation is used :

→ Ideal gas equation is PV = nRT.

→ Heat Capacity = mC = W = water equivalent.

→ There are three modes of transfer of heat i.e. conduction, convection and radiation.

→ Radiation mode is the fastest mode of heat transfer.

→ A body that neither reflects nor transmits any heat radiation but absorbs all the radiation is called a perfectly black body.

→ Q = mL
where Q = quantity of heat required for a change from one state to another.
L = Latent heat, m = mass of substance.

→ Melting point is a characteristic of the substance and it also depends 7 on the pressure.

→ Skating is possible on snow due to the formation of water below the skates. It is formed due to the increase of pressure and it acts as a lubricant.

→ The change from solid-state to vapour state without passing through the liquid state is called sublimation and the substance is said to be sublime.

→ Solid CO2 is called dry ice and it sublimes.

→ During the sublimation process, both the solid and the vapour states of a substance coexist in thermal equilibrium.

→ Melting: The change of state from solid to liquid is called melting.

→ Fusion: The change of state from liquid to solid is called fusion.

→ Melting point: The melting point is the temperature at which the solid and the liquid states of the substance co-exist in thermal equilibrium with each other.

→ Regelation: Regelation is the process of refreezing.

→ Vaporisation: Change of state from liquid to vapour is called vaporisation.

→ Boiling point: Boiling point is the temperature at which the liquid and the vapour states of the substance co-exist in thermal equilibrium with each other.

→ Normal melting point: The melting point of a substance at standard atmospheric pressure is called its normal melting point.

→ Normal boiling point: The boiling point of a substance at standard atmospheric pressure is called its normal boiling point.

Important Formulae:
→ \(\frac{T}{T_{t r}}=\frac{P}{P_{t r}}\)

→ Change in length is given by
Δ l = lo α Δθ

→ Change in area is given by
Δ S = So β Δθ.

→ Change in volume is given by
ΔV = Vo Y Δθ.
lt = lo(1 + α Δθ).
St = So (1 + β Δθ).
Vt = Vo (1 + γ Δθ).
where α, β & γ are called coefficient of linear, superficial and volume expansion respectively.

→ Thermal conductivity of a composite rod made of two conductors. of equal lengths and joined in series is given by
K = \(\frac{2 \mathrm{~K}_{1} \mathrm{~K}_{2}}{\mathrm{~K}_{1}+\mathrm{K}_{2}}\)

→ Temperature of the interface connecting two rods of different lengths d1 and d2 is given by
To = \(\frac{\mathbf{K}_{1} \mathrm{~d}_{2} \theta_{1}+\mathrm{K}_{2} \mathrm{~d}_{1} \theta_{2}}{\mathbf{K}_{2} \mathrm{~d}_{1}+\mathrm{K}_{1} \mathrm{~d}_{2}}\)
To = \(\frac{\mathrm{K}_{1} \theta_{1}+\mathrm{K}_{2} \theta_{2}}{\mathrm{~K}_{1}+\mathrm{K}_{2}}\) if their lengths are equal i.e. if d1 = d2.

→ If areas of the cross-section are equal, Then
K = \(\frac{\mathrm{K}_{1}+\mathrm{K}_{2}}{2}\)

→ \(\frac{\text { Change in temperature }}{\text { Time }}\) = KΔθ
where Δθ = difference of average temperature and room temperature.

→ Specific heat capacity of a substance is given by
C = \(\frac{\Delta \mathrm{Q}}{\mathrm{M} \Delta \theta}\)
ΔQ = MCΔθ.

→ The relation between Kelvin temperature (T) and the celcius temperature tc is
T = tc + 273.15.

→ Resistance varies with temperature as:
Rt = Ro(l + α Δθ)
where Ro = resistance at 0°C
Rt = resistance at t°C
α = temperature coefficient of resistance
Δθ = change in temperature.

→ Q = mL, where L = latent heat.

→ Temperature difference Δ°F equivalent to Δ°C is
ΔF = \(\frac{9}{5}\) × ΔC

→ Temperature difference ΔK equivalent to ΔF is
ΔF = \(\frac{9}{5}\)ΔK.

→ TK = Tc + 273.15