12th Class Physics Electric Charges and Fields Question Bank Case Based (MCQs) - Electric Charges and Fields

  • question_answer
    Two identical charges repel each other with a force equal to 10 mg wt when they are 0.6m apart in air.\[\left( g=10\,m{{s}^{-2}} \right)\] The value of each charge is:

    A) 2 mC               

    B) \[2\times {{10}^{-7}}mC\]

    C) \[2\,nC\]           

    D) \[2\mu C\]

    Correct Answer: D

    Solution :

    (d)\[2\mu C\] \[F=\frac{1}{4\pi {{\varepsilon }_{0}}}=\frac{{{q}_{1}}{{q}_{2}}}{{{d}^{2}}}\] \[\therefore \,\,\left( 10\times {{10}^{-3}} \right)\times 10=\frac{\left( 9\times {{10}^{9}} \right)\times {{q}^{2}}}{{{\left( 0.6 \right)}^{2}}}\] Or \[{{q}^{2}}=\frac{{{10}^{-1}}\times 3.6}{9\times {{10}^{9}}}=4\times {{10}^{-12}}\] Or \[q=2\times {{10}^{-6}}C=2\mu C\]


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