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NEET Sample Paper NEET Sample Test Paper-55

  • question_answer
    Two identical conducting spheres carrying different charges attract each other with a force F when placed in air medium at a distance d apart. The spheres are brought into contact with then taken to their original positions. Now the two spheres repel each other with a force whose magnitude is equal to that of the initial attractive force. The ratio between initial charges on the spheres is 

    A) \[-\left( 3+\sqrt{8} \right)only\]    

    B) \[-3+\sqrt{8}\,\,only\]

    C) \[-\left( 3+\sqrt{8} \right)\,\,or\,\,\left( -3+\sqrt{8} \right)\]  

    D) \[-\sqrt{8}\]

    Correct Answer: C

    Solution :

    \[\frac{K{{Q}_{1}}{{Q}_{2}}}{{{d}^{2}}}\,\,=\,\,\frac{K{{\left( \frac{{{Q}_{1}}+{{Q}_{2}}}{2} \right)}^{2}}}{{{d}^{2}}}\] \[{{({{Q}_{1}}+{{Q}_{2}})}^{2}}=\,\,4{{Q}_{1}}{{Q}_{2}}\]


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