JEE Main & Advanced Sample Paper JEE Main - Mock Test - 37

  • question_answer
    The ratio of electrostatic and gravitational forces acting between electron and proton separated by a distance\[5 \times  1{{0}^{-}}^{11}\,m\], will be (Charge on electron \[= 1.6 \times  1{{0}^{-}}^{19}C\], mass of electron \[= 9.1 \times  1{{0}^{-}}^{31}kg\], mass of proton \[=1.6\times 10\,kg\], \[\operatorname{G}=6.7\times 1{{0}^{-11}}\,N{{m}^{2}}/k{{g}^{2}}\])

    A) \[2.36 \times 1{{0}^{39}}\]                  

    B) \[2.36 \times  1{{0}^{40}}\]

    C) \[2.34 \times \,1{{0}^{41}}\]    

    D)        \[2.34 \times 1{{0}^{42}}\]

    Correct Answer: A

    Solution :

    Gravitational force \[{{F}_{G}}=\frac{G{{m}_{e}}{{m}_{p}}}{{{r}^{2}}}\] \[{{F}_{G}}= \frac{6.7\times 1{{0}^{-}}^{11}\times 9.1\times \,\,1{{0}^{-}}^{31}\times \,\,1.6\times {{10}^{-}}^{27}}{{{(5\times {{10}^{-11}})}^{2}}}\] \[=\,\,\,\,3.9\times {{10}^{-}}^{47}\,N\] Electrostatic force \[{{F}_{e}}=\frac{1}{4\pi {{\varepsilon }_{0}}}\frac{{{e}^{2}}}{{{r}^{2}}}\] \[{{F}_{e}}=\frac{9\times {{10}^{9}}\times 1.6\times {{10}^{-}}^{19}\times \,\,1.6\times {{10}^{-}}^{19}}{{{\left( 5\times {{10}^{-}}^{11} \right)}^{2}}}\] \[=\,\,\,9.22\times 1{{0}^{-\,8}}N\] So, \[\frac{{{F}_{e}}}{{{F}_{G}}}=\frac{9.22\times {{10}^{-8}}}{3.9\times {{10}^{-47}}}=2.36\times {{10}^{39}}\]


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