A) 6.3 min
B) 8.4 min
C) 12.6 min
D) 4.2 min
Correct Answer: A
Solution :
Heat evolved due to Joule's effect is used up in boiling water. \[VIt=ms\Delta t\]or \[t=\frac{ms\Delta t}{VI}\] We are given \[I=4A,V=200\,volt,\,m=1\,kg,\] \[\Delta t=(100-20){{\,}^{o}}C,s=4200\,J/kg{{\,}^{o}}C\] \[\therefore \] \[t=\frac{1\times 4200\times 80}{220\times 4}=6.3\,\min \]You need to login to perform this action.
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