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

  • question_answer
    The acceleration for electron and proton due to electrical force of their mutual attraction when they are \[1\,\overset{{}^\circ }{\mathop{A}}\,\]apart is:

    A) \[3.1\times {{10}^{22}}m{{s}^{-2}},\,1.3\times {{10}^{19}}m{{s}^{-2}}\]

    B) \[3.3\times {{10}^{18}}m{{s}^{-2}},\,3.2\,\times {{10}^{16}}m{{s}^{-2}}\]

    C) \[2.5\times {{10}^{22}}\,m{{s}^{-2}},\,1.4\times {{10}^{19}}m{{s}^{-2}}\]

    D) \[2.5\times {{10}^{18}}m{{s}^{-2}},\,1.3\times {{10}^{16}}m{{s}^{-2}}\]

    Correct Answer: C

    Solution :

    (c) \[2.5\text{ }\times \text{ }{{10}^{22}}\text{ }m{{s}^{-2}},1.4\times {{10}^{19}}\text{ }m{{s}^{-2}}\] Force of mutual attraction between an electron and a proton: \[F=\frac{1}{4\pi {{\varepsilon }_{0}}}\frac{{{e}^{2}}}{{{r}^{2}}}\] \[=\frac{\left( 9\times {{10}^{9}} \right){{\left( 1.6\times {{10}^{-19}} \right)}^{2}}}{{{\left( {{10}^{-10}} \right)}^{2}}}=2.3\times {{10}^{-8}}N\] Acceleration of electron \[=\frac{F}{{{m}_{e}}}\] \[=\frac{2.3\times {{10}^{-8}}}{9\times {{10}^{-31}}}=2.5\times {{10}^{22}}m{{s}^{-2}}\] Acceleration of proton\[=\frac{F}{{{m}_{p}}}\] \[=\frac{2.3\times {{10}^{-8}}}{1.66\times {{10}^{-27}}}=1.4\times {{10}^{19}}m{{s}^{-2}}\]


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