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12th Class Physics Electric Charges and Fields Question Bank MCQ - Electric Charges and Fields

  • question_answer
    Two insulated charged metallic spheres P and Q have their centres separated by a distance of 60 cm. The radii of P and Q are negligible compared to the distance of separation. The mutual force of electrostatic repulsion, if the charge on each is \[3.2\text{ }\times \text{ }{{10}^{-7}}\text{ }C\] is:

    A) \[5.2\times {{10}^{-4}}\,N\]

    B) \[2.5\times {{10}^{-3}}N\]

    C) \[1.5\times {{10}^{-3}}\,N\]                 

    D) \[3.5\times {{10}^{-4}}N\]

    Correct Answer: B

    Solution :

    (b) \[2.5\times {{10}^{-3}}N\] Here,\[{{q}_{1}}={{q}_{2}}=3.2\times {{10}^{-7}}\], \[r=60\,cm=0.6\,m\] Electrostatic force, \[F=\frac{1}{4\pi {{\varepsilon }_{0}}}\frac{{{q}_{1}}{{q}_{2}}}{{{r}^{2}}}\] \[=\frac{\left( 9\times {{10}^{9}} \right){{\left( 3.2\times {{10}^{-7}} \right)}^{2}}}{{{\left( 0.6 \right)}^{2}}}\] \[=2.56\times {{10}^{-3}}N\]


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