Reason heating conductor lies in the fact that the energy of moving it electrons (in other words, the energy current) sequential collision of particles with ions of a molecular lattice of the metal element is converted into a warm type of energy, or Q, and formed the concept of "thermal capacity".
work is measured by the current international system of SI units by applying the joules (J), output current is defined as "W" (W).Departing from the system in practice can be used including non-SI units, the current measuring work.Among them Wh (W × h), kilowatt-hour (abbreviated kW × h).For example, 1 × W h denotes the current work with a specific power of 1 watt and the duration of time for one hour.
If the electrons move along a fixed wire, metal, in this case, all the useful work produced by the current is distributed to the heating of the metal structure, and on the basis of the provisions of the law of conservation of energy, it can be described by the formula Q = A = IUt = I2Rt = (U2/ R) * t.Such relations with a precision expressed known law of Joule.Historically, it was first determined empirically by Joel D. scientists in the mid-19th century, and at the same time, regardless of it another scientist - E.Lentsem.Practical application of thermal power found in technical performance with the invention in 1873 by Russian engineer Alexander Ladygin ordinary incandescent lamps.
Thermal output current is activated in a number of electrical appliances and industrial installations, namely in thermal instrumentation, heating such as electric ovens, electric welding and's inventory equipment are very common appliances in the electric heating effect - boilers, irons, kettles, irons.
find yourself thermal effect in the food industry.With a high proportion of the opportunity to apply electric-heating, which guarantees thermal power.It is caused by the fact that the current and thermal capacity, affecting the food, which has a certain degree of resistance causes it heats evenly.One can cite as an example the way made sausages: through a special dispenser minced meat enters the metal molds, the walls of which also serve as electrodes.There is provided a constant uniform heating over the entire area and volume of the product to the desired temperature is maintained optimal biological value of the food, along with these factors and the duration of the technological works are the least energy consumption.
specific heat capacity of the electric current (ω), in other words - the amount of heat that is released per unit volume for a certain unit of time, is calculated as follows.Elementary cylindrical volume conductor (dV), with a cross-section ductor dS, length dl, parallel to the direction of the current, and resistance is the equation R = p (dl / dS), dV = dSdl.
According to the definitions of the law Joule, in the allotted time (dt) in the volume of commitments we highlighted the level of heat equal to dQ = I2Rdt = p (dl / dS) (jdS) 2dt = pj2dVdt.In this case, ω = (dQ) / (dVdt) = pj2 and using Ohm's law is to establish the current density j = γE and the ratio of p = 1 / γ, we immediately obtain an expression ω = jE = γE2.It is in differential form gives the concept of the law of Joule.
