A) 1kW, 60 kJ
B) 0.5 kW, 30 kJ
C) 10 kW,600 kJ
D) none of these
Correct Answer: A
Solution :
When electric current flows through an electric heater, the heater becomes hot. This is known as Joules heating effect, the rate of production of heat is given by \[P=\frac{H}{t}=Vi\] where V is voltage, i is current and t is time. Given, \[V=250\] volt, \[i=4\,A,t=1\,\min =60\,s\] \[\therefore \] Power, i.e., rate of production of heat is \[H250\times 4=1000\,\,W\] \[=1\,kW\] Energy consumed is \[H=Pt\] \[=1000\times 60\] = 60000 J = 60 kJ
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