An electric kettle takes 4A current at 220 V. How much time will it take to boil 1 kg of water from temperature 20⁰C? The temperature of boiling water is 100⁰C

Options

(a) 12.6 min
(b) 4.2 min
(c) 6.3 min
(d) 8.4 min

Correct Answer:

6.3 min

Explanation:

Power = 220 V × 4A = 880 watt = 880 J/s

Heat needed for raising 1 kg of water through 80°C = ms.ΔT × 4.2 J/cal = 100 g × 1 cal/g × 80 × 4.2 J/cal

Therefore, Time taken = (1000 × 1 × 80 × 4.2) / 880 = (336 × 10³) 880 = 382 s = 6.3 min