Thermal conductionThermal conduction is the transfer of energy resulting from temperature differences between adjacent parts of a body. Thermal conductivity is recognized as the exchange of energy between molecules and electrons in the conducting medium. The rate of heat flow in a rod of any material is proportional to the cross-sectional area of ​​the rod and the temperature difference between the ends and inversely proportional to the length; that is, the speed H is equal to the ratio between the section A of the rod and its length l, multiplied by the temperature difference (T2 - T1) and by the thermal conductivity of the material, indicated by the constant k. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get Original Essay A substance with large thermal conductivity k is a good conductor of heat, while one with small thermal conductivity is a poor conductor of heat or a good heat insulator. Typical values ​​are 0.093 kilocalories/second meter-°C for copper (a good thermal conductor) and 0.00003 kilocalories/second meter-°C for wood (a poor thermal conductor). Convection is the transfer of internal energy into or out of an object by the physical motion of a surrounding fluid which transfers the internal energy along with its mass. Although heat is initially transferred between the object and the fluid by conduction, most of the energy transfer comes from the motion of the fluid. Convection can occur suddenly through the creation of convection cells or it can be forced by pushing the fluid through the object or from the object through the fluid. Spontaneous convection can occur due to: exposed surface area viscosity density conductivity acceleration due to gravity Natural convection occurs because most fluids have a tendency to expand when heated, i.e. they become less dense and rise as a result of increased buoyancy. The circulation that occurs in this way explains the uniform heating of water in a kettle or air in a heated room: the heated molecules expand the space in which they are located. they move with greater speed against each other, they rise, then they cool and come closer together again, with an increase in density and consequent sinking. Forced convection involves the transport of fluid by methods other than those that occur from the variation of density with temperature. Examples of convection are the movement of air through a fan or water through a pump. Atmospheric convection currents can be created by local heating effects such as solar radiation or contact with cold surface masses. These convection currents move mostly vertically and are responsible for many atmospheric existences, such as clouds and thunderstorms. Thermal Radiation Thermal radiation is a process by which energy, in the form of electromagnetic radiation, is emitted from a heated surface in all directions and travels directly to its point of absorption at the speed of light. Thermal radiation does not require a dominant medium to transport it. Thermal radiation occurs in wavelengths ranging from the longest infrared rays through the visible light spectrum to the shortest ultraviolet rays. The intensity and distribution of energy within this wavelength range depends on the temperature of the emitting surface. The total radiant heat energy emitted by a surface is proportional to the fourth power of its total temperature (the Stefan-Boltzmann law). Please note: this is just an example. Get an item now.