#### Conduction, Temperature Gradient and Thermal Conductivity

This note provides us an information about conduction, When heat is transferred through the medium but without the actual motion of transfer of particles in the medium, then this process is called conduction. The temperature gradient The rate of fall of temperature with distance in the direction of heat flow is called the temperature gradient. and thermal conductivity the thermal conductivity of the substance can be defined as the quantity of heat transferred through the surface having 1 m2 area of the cross-section of each, separated by a distance of 1 m and 1 K difference in temperature between them in 1 second time.

#### Thermal Conductivity by Searle's Method and Heat Radiation

This note provides us an information about Thermal Conductivity by Searle's Method and Heat Radiation The intensity of heat radiation is inversely proportional to the square of the distance of the surface from the source of heat radiation which verifies the inverse square law of heat radiation. This note provides us an information on thermal conductivity by Searle's method and heat radiation. The intensity of heat radiation is inversely proportional to the square of the distance of the surface from the source of heat radiation which verifies the inverse square law of heat radiation.

#### Black Body and Stefan-Boltzmann Law

A perfect black body is one which absorbs heat radiation of all wavelengths that fall upon it. This note provides an information about black body and Stefan-Boltzmann law.

#### Heat Radiation and Surface Temperature of the Sun

According to the theory of heat exchange, every body radiates heat radiation continuously at all temperatures. This note provides us as information on heat radiation and surface temperature of the sun. Stefan's law of black body radiation can be used to determine the temperature of sun. We know that the sun is radiating heat radiation in all direction.