A) 2
B) 3
C) 4
D) 6
Correct Answer: A
Solution :
Suppose the balls having charges \[{{Q}_{1}}\,\,and\,\,{{Q}_{2}}\] respectively. Initially: Finally, \[\,\frac{{{Q}_{1}}+{{Q}_{2}}}{2}\] \[\,\frac{{{Q}_{1}}+{{Q}_{2}}}{2}\] \[F'\,\,=\,\,\frac{k{{\left( \frac{{{Q}_{1}}+{{Q}_{2}}}{2} \right)}^{2}}}{{{\left( \frac{r}{2} \right)}^{2}}}\,\,=\,\,\frac{k{{({{Q}_{1}}+{{Q}_{2}})}^{2}}}{{{r}^{2}}}\] It is given that\[F=4.5\,F\], so \[\frac{k{{({{Q}_{1}}+{{Q}_{2}})}^{2}}}{{{r}^{2}}}\,\,=\,\,4.5\,k.\frac{{{Q}_{1}}{{Q}_{2}}}{{{r}^{2}}}\] \[\Rightarrow \,\,\,{{({{Q}_{1}}+{{Q}_{2}})}^{2}}=\,\,4.5\,{{Q}_{1}}{{Q}_{2}}\]You need to login to perform this action.
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