Question 662: Current Electricity

Question

An electric kettle takes 4 A current at 220 V. How much time will it take to boil 1 kg of water from temperature 20
o
C ? The temperature of boiling water is 100
o
C

Accepted Answer

Power = 220 V ÃÂ 4 A = 880 watts. = 880 J/s.
Heat needed to raise the temperature of 1 kg water through 80ÃÂ°C
= ms.$$\Delta $$T ÃÂ 4.2 J/cal
= 1000 g ÃÂ 1 cal/g ÃÂ 80 ÃÂ 4.2 J/cal.
$$ 	herefore $$ Time taken = $${{1000 	imes 1 	imes 80 	imes 4.2} \over {880}} = {{336 	imes {{10}^3}} \over {880}}$$
= 382 s = 6.3 min.

Answer

12.6 min

Answer

4.2  min

Answer

6.3 min

Answer

8.4 min

Current Electricity

An electric kettle takes 4 A current at 220 V. How much time will it take to boil 1 kg of water from temperature 20 o C ? The temperature of boiling water is 100 o C

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