A) 2.71 V
B) 1.95 V
C) 1.68 V
D) 0.52 V
Correct Answer: B
Solution :
Key Idea: The potential difference of a cell is less than the emf of the cell. When we connect the plates of a cell by a wire, an electric current flows in the wire from positive plate towards the negative plate. From law of conservation of energy. Work done \[={{W}_{(external\text{ }circuit)}}\] \[+{{W}_{(internal\text{ }circuit)}}\] or \[E\,i\,\,t=V\,\,i\,\,t+{{i}^{2}}r\,t\] \[\Rightarrow \] \[V=E-ir\] \[\Rightarrow \] \[V=E-\left( \frac{E}{R+r} \right)\,\,r\] Putting the numerical values, we have \[V=2-\left[ \frac{2}{3.9+0.1}\times 0.1 \right]\] \[=2-\frac{0.2}{4}\] \[=2-0.05=1.95\,\,V\]You need to login to perform this action.
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