A 500-W-200V electric kettle is used to prepare 4cups of tea How long will it take? Assume that a cup contains 250cc of water. Specific heat capacity of water `4200Jkf^(-1)K^(-1)` and the initial temeprature of water `250^(@)C`. Also calcuate the cost of prepare tea if 1 B.O.T. costs 35 paise.
