An electric kettle rated 2.1 kilowatt contains 1 kg of water.Assuming no heat loss and neglecting the thermal capacities of kettle,how long will it take to start to boil the water if its initial temp is 20C?

Question

14344 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2017-12-23T05:34:32

Given the power rating of the electrical kettle #P=2.1kW#

If time taken to raise the temperature of 1 kg of water from #20^@ to 100^@C# is t sec, then the electrical energy required for this will be

#=Pt=2.1t" "kJ#

Again the heat energy reqired to raise the temperature of 1 kg of water from #20^@ to 100^@C# is

#1xx4200xx(100-20)J=336KJ#

So #2.1t=336#

#=>t=336/2.1=160s=# 2 min 40 sec