An electric kettle takes $4\, A$ current at $220\, V$. How much time will it take to boil $1\, kg$ of water from room temperature $20\,^\circ C$ ? The temperature of boiling water is $100\,^\circ C$ .................. $minutes$
Medium
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(b) Electric power consumed by kettle $P = 220 \times 4\,W$
Heat required
$H = 1000 \times 1\,(100 - 20) = 1000 \times 80\,\,cal$$ = 4200 \times 80\,\,J$
$P = \frac{H}{t} \Rightarrow \,H = P \times t$
$220 \times 4 \times t = 4200 \times 80$ $ \Rightarrow $ $t = 6.3\,\,$ $minutes$
Heat required
$H = 1000 \times 1\,(100 - 20) = 1000 \times 80\,\,cal$$ = 4200 \times 80\,\,J$
$P = \frac{H}{t} \Rightarrow \,H = P \times t$
$220 \times 4 \times t = 4200 \times 80$ $ \Rightarrow $ $t = 6.3\,\,$ $minutes$
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