Mechanical Properties of Fluids
An electric kettle takes 4 A current at 220 V. How much time will it take to boil 1 kg of water from temperature 200 C? The temperature boiling water is 100o C.
6.3 min
8.4 min
12.6 min
4.2 min
A.
6.3 min
Heat is evolved due to joule's effect is used up in boiling water.
such as
Vlt = msΔt
t = msΔt/VI
Putting under given values
I= 4A, V= 220 volt, m =1 kg,
Δt = (100-20)oC, s = 4200 J/kgo C
t = 1 x 4200 x 80 / 220 x 4 = 6.3 min
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