In a home experiment , Ram brings a new electric kettle with unknown power rating . He puts `1` litre water in the kettle and switches on . But to his dismay , the temperature becomes constants at `60^(@)C` after some time. The room temperature is `20^(@)C`. Ram gets bored and switches off the kittle . He sees that during first `20`s water cools down by `2^(@)C`.
What is the wattage of the kettle

Options

A. `840W`
B. `1W`
C. `100W`
D. `420W`

Answer

B

Explanation

Ans (D)
`(DeltaQ)/(t) =(1 xx 4200 xx 2)/(20)J//sec = 420W`