One kg of water, at $20^{\circ} \mathrm{C}$, is heated in an electric kettle whose heating element has a mean (temperature averaged) resistance of $20 \Omega$. The rms voltage in the mains is 200 V . Ignoring heat loss from the kettle, time taken for water to evaporate fully, is close to [Specific heat of water $=4200 \mathrm{~J} /\left(\mathrm{kg}^{\circ} \mathrm{C}\right)$, Latent heat of water $=2260 \mathrm{~kJ} / \mathrm{kg}]$