(ii).conversion from 0 C to Fahrenheit:- 0 C= 5 9. (F- 32) (ii).conversion from Fahrenheit to 0 C:- F= 9 5 C + 32 Relation between different scales:-

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1 Thermal properties of matter Heat: - Heat is a form of energy transferre between two (or more) systems or a system an its surrounings by virtue of temperature ifference. **Conventionally, the heat energy Q supplie to a boy is taken to be positive (+Q) an the heat energy given out of a boy is taken to be negative (-Q). S.I unit of heat = Joule(J) ; C.G.S unit = Calorie. [ 1 Calorie= 4.2 Joule] Temperature: - It is a measure of hotness or colness of a boy. Thermometer: a evice which is use to measure the temperature of a boy is known as thermometer.commonly use thermometer scales are: (i) Celsius scale ( 0 C) (ii) Kelvin scale (K) (iii) Fahrenheit scale ( 0 F) (i).conversion from Kelvin to 0 C. t 0 C = (273+t)K (ii).conversion from 0 C to Fahrenheit:- 0 C= 5 9 (F- 32) (ii).conversion from Fahrenheit to 0 C:- F= 9 5 C + 32 Relation between ifferent scales:- C F = 180 = K * 0 K is calle absolute zero. e.g: 1. Temperature of the human boy is F.fin the corresponing temperatures on the Celsius scale an Kelvin scale. (Ans: C = 309.9K) Thermal Expansion:- 1.Expansion of soli:- The change in temperature of a boy may change its length, area or volume. The fractional change in imension [ratio of change in imension to original imension = l l ] is proportional to change in temperature ( T).. 2. Expansion of liquis:- A liqui has volume expansion only. It requires a container to hol the liqui. When a liqui is heate, the container also expans. *Anomalous expansion of water: - Generally volume of liqui increases with temperature.when water is heate, its volume starts to ecrease from 0 0 C an reaches minimum at 4 0 C. Hence ensity of water is maximum at 4 0 C. Consequences of anomalous expansion of water:- In col countries, uring winter the atmospheric temperature reuces. When it reaches 4 0 C, the water will have maximum ensity an sinks to bottom. With further cooling, the top layer becomes ice. Since ice is a ba conuctor of heat, the lower layer remains at 4 0 C.thus aquatic animals are save.

2 Heat Capacity: - It is the quantity of heat require to raise the temperature of the boy through 1K. Unit: J/K Dimension = [M L 2 T -2 K -1 ] Specific heat capacity:- It is the quantity of heat require to raise the temperature of unit mass of the substance through 1K. Unit: Jkg -1 K -1 Dimension = [ L 2 T -2 K -1 ] Molar specific heat capacity [C]:- It is the quantity of heat require to raise the temperature of 1 mole of substance through one Kelvin. Unit: J mol -1 K -1 Relation between quantity of heat & raise of temperature:- The quantity of heat supplie to a boy of mass m an specific heat c to raise the temperature through θ 0 C is given by : Q = mcθ. Specific heat of gases:- Specific heat capacity at constant volume [ CV]:- It is the amount of heat require to raise the temperature of unit mass of the gas through one Kelvin keeping its volume constant. Molar Specific heat capacity at constant volume [ CV]:- It is the amount of heat require to raise the temperature of 1 mole of the gas through one Kelvin keeping its volume constant. Specific heat capacity at constant pressure [ CP]:- It is the amount of heat require to raise the temperature of unit mass of the gas through one Kelvin keeping its pressure constant. Molar Specific heat capacity at constant pressure [ CP]:- It is the amount of heat require to raise the temperature of 1 mole of the gas through one Kelvin keeping its volume constant. 1. Why CP is greater than CV? Ans: When one mole of a gas heate at constant volume, the heat supplie is utilize only to increase the internal energy (temperature) of the gas. When it is heate at constant pressure, the heat supplie is use not only for increasing the internal energy but also for oing external work uring expansion. Hence CP > CV. Mayer s relation:- CP - CV = R; Where R- universal gas constant R= 8.31Jmol -1 K -1 or Jkg -1 K -1 Ratio of specific heats CP CV = γ Degrees of freeom:- It is the total number of inepenent quantities require to escribe the position or motion of the system completely. Degrees of freeom of gas molecules:- 1.Monoatomic molecule:- It has only one atom (Helium, Neon..) **It is capale of only translator motion in free space. Hence it has three egree of freeom. 2.Diatomic molecule:- It has two atom (H2, O2..) **It can have three translational an two rotational motions. Hence, egree of freeom is 5.

3 3.Triatomic molecule:- Molecule such as CO2, NO2 has three translational an three rotational egrees of freeom. Hence, egrees of freeom is 6. Law of equipartion of energy:- For a ynamical system in thermal equilibrium, the total energy of the system is equally ivie among the various egrees of freeom. ##The share of energy of each egree of freeom = ½ KT; where K is Boltzmann constant an T is the absolute temperature. Change of state:- Fusion:- The change from soli to liqui is known as fusion(melting) an the reverse is known as soliification. Specific latent heat of fusion of a soli (L):- It is the quantity of heat require to convert unit mass of the soli at its melting point into liqui at the same temperature. Unit: J/kg Vapouristion:- The change from liqui to vapour is known as vapourisation an the reverse is known as conensation. Specific latent heat of vaporisation of a liqui: It is the quantity of heat require to convert unit mass of liqui at its boiling point into vapour at the same temperature. Quantity of heat:- Quantity of heat require to convert a substance of mass m an specific latent heat L from one state to other state is Q= ml. **A soli at 0 0 C is heate to convert it into its vapour. Draw a graph connecting temperature an the quantity of heat supplie** Heat transfer:- Different moes of heat transfer are (1).Conuction, (2).Convection & (3).Raiation. Conuction: - It is the moe of heat transfer from a hot region to col region without any boily movement of the molecule of the intervening meium. Temperature graient:- It is the rate of change of temperature with istance. θ (θ1 -θ2 ) x = where θ1,θ2 temp. of two sections & - istance between two sections.

4 Coefficient of thermal conuctivity:- When a substance attains a steay state, the quantity of heat conucte normally through any section is irectly proportional to (i).area of cross section A Q α A (θ1 -θ2 ) (ii).temperature graient Q α & (iii).time uring which heat is conucte Q α t (θ1 -θ2 ) (θ1 -θ2 ) i.e., Q α A t = λ A t ; λ-coefficient of thermal conuctivity. (θ1 -θ2 ) If A=1, =1 & t=1 then Q = λ Coefficient of thermal conuctivity (λ) of a substance is efine as the quantity of hear conucte normally per secon through unit area of the substance per unit temperature graient when the substance attains steay state. Q Unit : λ = A(θ1 -θ2 ) t = J m m 2 Ks = J m-1 K -1 s -1 Convection:- It is the moe of heat transfer from a hot to a col region with actual boily movement of the particles of the intervening meium. Application:- 1. Lan breeze, sea breeze an trae wins 2. Use in ventilations. Raiation:- It is the moe of transfer of heat from hot region to col region without the help of an intervening meium. Characteristics of thermal raiation:- 1. They are electromagnetic waves travelling with a spee of 3x10 8 m/s in vacuum. 2. Thermal raiation lies in the infrare region. 3. They can be reflecte or refracte like light. 4. They exhibit interference an iffraction. 5. They exert pressure on boies on which they fall. Black boy an black boy raiation:- A perfectly black boy is that which absorbs completely the raiations of all wave lengths incient on it. A perfect black boy is a goo absorber of raiant energy. When a perfect blackboy is heate to a suitable high temperature, it emits raiation of all wavelengths in a particular region of the electromagnetic spectrum. The raiation emitte by perfect black boy is calle black boy raiation. Define emissive power an absorptive power:- Emissive power: (ε ) :- emissive power of the surface of a boy for a given wavelength λ at a given temperature is efine as the amount of energy emitte per secon per unit area of the surface. For perfect black boy, ε =1. Absorptive power ( aλ ) :- absorptive power of the surface of a boy for a given wavelength λ is the ratio of the quantity of heat absorbe by it to the quantity of heat incient on it. Absorptive power of perfect black boy = 1

5 Distribution of energy in a black boy raiation:- Emissive power plotte against wavelength is calle energy istribution curve. 1. As the temperature rises the intensity of raiation corresponing to each raiation increases. 2.The peak of the curve shift towars shorter wavelength as temperature rises. Wien s isplacement law:- It states that the wavelength (λm) of raiation corresponing to the maximum energy emitte by a block boy is inversely proportional to the absolute temperature(t) of the black boy. λm α 1 T λm T = b [b= mk wien s constant] Stefan s law:- It states that the total raiant energy emitte per secon from unit area of the surface of a blackboy is irectly proportional to fourth power of its absolute temperature. Eα T 4 E= σ T 4 [σ-stefan s constant = 5.67 x10-8 W m -2 K -4 ] Newtons law of cooling:- The law states that the rate of loss of heat of the boy is irectly proportional to the ifference of temperature of the boy an the surrounings. -Q t α T2 T1 If a boy of mass m an specific heat capacity c cools from θ1 to θ2 in a time t secon in a surrouning at θ 0 C. Accoring to Newtons law, mc(θ1 -θ2 ) (θ1 +θ2 ) t α [ 2 - θ0] Note:- Newton s law is applicable only when the ifference between the boy an the surrouning is small *Rate of cooling is irectly proportional to excess of temperature.