Question

An electric kettle of 2000 Wis used to boil 20 litres of water. Find the time required to boil to the water from its initial temperature of `20^(@)C`. (Take specific heat of water as `4200 J kg^(-1) K^(-1)`. Density of water `= 1000kg m^(-3)`)

Answer 1

(i) Power `P = E/t`
Energy supplied by the electric kattle is used to increase the temperature of 20 litres of water from `20^(@)C` to `100^(@)C`. But heat energy `Q = msDeltatheta`.
Calculate the heat energy absorbed by the water.
Substituting the value of energy and power in equation (1) we can determine the time.
(ii) 56 minutes