A) 15 V
B) 30 V
C) 14 V
D) 18 V
Correct Answer: C
Solution :
It is clear that the two cells oppose each other hence, the effective emf in closed circuit is 18 ? 2 = 6 V and net resistance is 1 + 2 = 3\[\Omega \] (because in the closed circuit the inters. resistances of two ceils are in series). The current in circuit will be in direction of arrow shown in figure. \[I=\frac{effective\,emf}{total\,resis\tan ce}=\frac{6}{3}=2\,A\] The potential difference across V will be same as the terminal voltage of either cell. Since, current is drawn from the cell of 18 volt, hence, \[{{V}_{1}}={{E}_{1}}-i{{r}_{1}}\] \[=18-(2\times 2)=18-4=14\,V\] Similarly, current enters in the cell of 12 V, hence, \[{{V}_{2}}={{E}_{2}}+i{{r}_{2}}\] \[=12+2\times 1\] \[=12+2=14\,V\] Hence, V = 14 VYou need to login to perform this action.
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