Q.

Two conducting wires of the same material and of equal lengths and equal diameters are first connected in series and then in parallel in a circuit across the same potential difference. The ratio of power produced in series and parallel combinations would be:

1 1 : 2  
2 2 : 1  
3 1 : 4  
4 4 : 1  

Ans.

(3)

As the two conducting wires are of the same material, equal lengths and equal diameters. They will have the same resistance.

Let the resistance of each wire be R and applied potential difference, V

Rseries=R1+R2            = R+R=2RPseries=V2Rseries            = V2(2R)                  (i)

1Rparallel=1R1+1R2                = 1R+1RRparallel  = R2Pparallel = R2Pparallel = V2Rparallel              =  2V2RDividing equation (i) by equation (ii) PseriesPparallel=14