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. 6.4 mimutes
B. 6.3 mimutes
C. 12.6 mimutes
D. 12.8 mimutes

Answer 1

Correct Answer - B
(b) Electric power consumed by kettle `P = 220 xx 4 W`
Heat require
`H = 1000 xx 1 (100 - 20) = 1000 xx 80 cal`
`= 4200 xx 80 J`
`P = (H)/(t) implies H = P xx t`
`:. 220 xx 4 xx t = 42000 xx 80 implies T = 6.3` minutes