The heater coil of an elecric kettle is rated at 2000W,200V, How much time will in take is rasing the temperature of 1 litres of water from `20^(@)C` to `100^(@)C`. Assuming that only 80% of the total heat energy produced by the heater coil is used in raising the temperature of water. Density of water heater coil is used in raising the temperture of water. density of water =`1g cm^(-3)` and specific heat of water `= 1 "cal" g^(-1) .^(@)C^(-1)`.