An electric kettle takes $4 \mathrm{~A}$ current at $220 \mathrm{~V}$. How much time will it take to boil $1…

An electric kettle takes $4 \mathrm{~A}$ current at $220 \mathrm{~V}$. How much time will it take to boil $1 \mathrm{~kg}$ of water from temperature $20^{\circ} \mathrm{C}$ ? The temperature of boiling water is $100^{\circ} \mathrm{C}$.
  1. $4.2 \mathrm{~min}$
  2. $6.3 \mathrm{~min}$
  3. $8.4 \mathrm{~min}$
  4. $12.6 \mathrm{~min}$

Solution

$\begin{aligned} & \text { Vit }=m c \Delta \theta \\ & t=\frac{1 \times 4200 \times 80}{220 \times 4}=381.8 \mathrm{~s}=6.36 \mathrm{~min} \end{aligned}$ .

Asked in: NEET 2008 (Mains)

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