Resistive Heating ,
also known as Joule heating and Ohmic heating,
is the process by which the passage of an electric
current through a conductor releases heat. It was first
studied by James Prescott Joule in 1841. Joule immersed
a length of wire in a fixed mass of water and measured
the temperature rise due to a known current flowing
through the wire for a 30 minute period. By varying the
current and the length of the wire he deduced that the
heat produced was proportional to the square of the
current multiplied by the electrical resistance of the
wire.Joule
heating is referred to as resistive heating
because of its relationship to
Ohm's Law. It forms the basis for the myriad of
practical applications involving electric heating.
However, in applications where heating is an unwanted
by-product of current use (e.g., load losses in
electrical transformers) the diversion of energy is
often referred to as resistive losses. The use of
high voltages in electric power transmission systems is
specifically designed to reduce such losses in cabling
by operating with commensurately lower currents. The
ring circuits, or ring mains, used in homes are another
example, where power is delivered to outlets at lower
currents, thus reducing Joule heating in the wires.
