Calculation formula of converting electricity into heat

Q=I？ Rt, Joule's law is a law that quantitatively explains the transformation of electric energy into heat energy by conducting current.

The content is: the heat generated by current passing through a conductor is proportional to the quadratic power of current, to the resistance of the conductor, and to the electrifying time. The mathematical expression of Joule's Law: Q=I? rt； For pure resistance circuits, it can be deduced that Q = W = PtQ = UItQ=(U? /R)t .

Joule's law is an experimental law, which is applicable to any conductor and has a wide range, and all circuits can do it. When it comes to the thermal effect of current, for example, it is necessary to calculate the heat released when the current passes through a certain circuit; Joule's law can be used to compare the heat released by a circuit or conductor, that is, to consider the requirements of the circuit from the perspective of current thermal effect.

Extended data:

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It should be noted that W = (u 2/r) t is derived from Ohm's law, which can only be established if the work done by current (pure resistance circuit) completely converts electric energy into heat energy. Such as electric furnace, soldering iron and other electrical appliances, these two formulas are equivalent to Joule's law? .

When using Joule's law formula, each physical quantity in the formula should correspond to the same conductor or the same circuit, and the corresponding relationship is the same as when using Ohm's law. When several physical quantities appear in the topic, the angle code should be added to show the difference.

Note: W=Pt=UIt applies to all circuits, while W=I? Rt = (u 2/r) t is only used for pure resistance circuits (all used for heating).

Baidu Encyclopedia-Joule Law