Thermal Properties of Matter

Heat Transfer

  • The phenomenon of heat transfer without the actual displacement of the particles of the medium called conduction.
  • The phenomenon of heat transfer takes place with the actual motion of particles called convection.
  • The phenomenon of heat transfer takes place without any medium called Radiation.
  • The process of heat conduction from not end to cold end of a conductor. No heat is absorbed by it at any section called steady state.
  • Coefficient of thermal conductivity is the quantity of heat required to rise the temperature of unit length through 1ºC in unit time \tt K=\frac{Q.\ell}{\Delta \left(\theta_{1}-\theta_{2}\right)t}
  • The Thermal resistance of a body is a measure of its opposition to the flow of heat through it \tt K=\frac{\theta_1-\theta_2}{\left(Q/t\right)} (or) R = l/kA
  • Thermal diffusivity is the ratio of coefficient of thermal conductivity to thermal of capacity per unit volume.
  • Conduction takes place in solids only where as conversion takes plane in liquids and gases.
  • Natural convection takes heat from the bottom to the top while forced convection may takes place in any direction.
  • Radiation is the phenomenon of transfer of heat without necessity of material medium.

View the Topic in this video From 13:07 To 41:47

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1. The amount of heat transmitted through a conductor is given by
Q=\frac{kA\Delta\ Tt}{l}

2. \tt H=KA\frac{T_{C}-T_{D}}{L} The constant of proportionality K is called the thermal conductivity of the material.

3. For a body with emissivity e, the relation modifies to \tt H=e\sigma A \left({T^{4}-T_s^4}\right)

4. For a body, which is a perfect radiator, the energy emitted per unit time (H) is given by H = AσT4