A) 4
B) 6
C) 8
D) 9
Correct Answer: B
Solution :
Let R and m be the resistance and mass of the first wire, then the second wire has resistance 2R and mass 2m. Let E = emf of each cell, S = specific heat capacity of the material of the wire. For the first wire, current \[{{i}_{1}}=\frac{3E}{R}\] and \[i_{1}^{2}Rt=mS\Delta T\] For the second wire, \[{{i}_{2}}=\frac{NE}{2R}\] and \[i_{2}^{2}(2R)t=2mS\Delta T\]. Thus, \[{{i}_{1}}={{i}_{2}}\] or \[N=6\].
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