# An electric iron of resistance

Question.
An electric iron of resistance $20 \Omega$ takes a current of 5 A. Calculate the heat developed in $30 \mathrm{~s} .$

solution:

Here, resistance, $R=20 \Omega$, current, $I=5 A$, time, $t=30 \mathrm{~s}$.

Heat produced, $\mathrm{H}=\mathrm{I}^{2} \mathrm{R} \mathrm{t}=(5)^{2} \times 20 \times 30$

$=1.5 \times 10^{4} \mathrm{~J}$

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