Question

An electric kettle takes `4 A` current at `220 V`. How much time will it take to boil `1 kg` of wate from temperature `20^(@)C`? The temperature of boiling water is `100^(@)C`
A. 12.6 min
B. 4.2 min
C. 6.3 min
D. 8.4 min

Answer 1

Correct Answer - C
Heat required to boil water
Q = mc`DeltaT`
`=1xx1xx(100-20)="80 kcal"`
Heat given by supply
`H=v.i.t=200xx4xxt`
`rArr 200xx4xxt=80,000`
`t=(80,000)/(220xx4)`
`=(1000)/(11)sec`
`=(1000)/(11xx60)=1.5"min"`