An electric kettle takes 4 A current at 220 V. How much time will it take to boil 1 kg of water from room temperature 20^{0}C? The temperature of boiling water is 100^{0}C

  • Option 1)

    6.4 minutes

  • Option 2)

    6.3 minute

  • Option 3)

    12.6 minutes

  • Option 4)

    12.8 minutes

 

Answers (1)

As we learnt in 

Power dissipated in external resistance -

P=(\frac{E}{R+r})^{2}R

-

 

 Total energy required = m s \DeltaT

= 1000 \times 1 cal/g \times 80

= 80000 \times 4.2 J = 336000J

\therefore time \ required = \frac{energy}{power}= \frac{33600}{VI}

=\frac{33600}{220\times4}=6.3\ min

 


Option 1)

6.4 minutes

Incorrect

Option 2)

6.3 minute

correct

Option 3)

12.6 minutes

Incorrect

Option 4)

12.8 minutes

Incorrect

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