One kg of water, at 20
o
C, 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 J/(kg
o
C), Latent heat of water = 2260 kJ/kg]