State Joule's law of heating and write its mathematical form.
State Joule's law of heating and write its mathematical form.
It states that when current is passed through a conductor the heat produced across it is
$(i)$ directly proportional to the square of current through the conductor i.e.
$H \propto I ^{2}$ $....(1)$
$(ii)$ directly proportional to the resistance of the conductor i.e.,
$H \propto R$ $.....(2)$
$(iii)$ directly proportional to the time for which the current is passed i.e.
$H \propto t$ $...(3)$
Combining the above three equations, we have
$H \propto I ^{2} R t$
or $H =\frac{ I ^{2} R t}{ J }$ calories $...(4)$
It is expressed as $H = I ^{2} Rt$ Joules.
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