JEE Main & Advanced Physics Electrostatics & Capacitance Question Bank Electric Field and Potential

  • question_answer
    An infinite line charge produce a field of \[7.182\times {{10}^{8}}\,N/C\] at a distance of 2 cm. The linear charge density is [MH CET 2004]

    A)                    \[7.27\times {{10}^{-4}}\,C/m\]

    B)                                      \[7.98\times {{10}^{-4}}\,C/m\]

    C)                    \[7.11\times {{10}^{-4}}\,C/m\]

    D)                                      \[7.04\times {{10}^{-4}}\,C/m\]

    Correct Answer: B

    Solution :

                 Relation for electric field is given by \[E=\frac{\lambda }{2\pi {{\varepsilon }_{0}}r}\] (Given :\[~E=\text{ }7.182\times {{10}^{8}}N/C\]) \[r=\text{ }2cm=\text{ }2\times {{10}^{2}}m\] \[\frac{1}{4\pi {{\varepsilon }_{0}}}=9\times {{10}^{-9}}\] Þ \[\lambda =2\pi {{\varepsilon }_{0}}rE=\frac{2\times 2\pi {{\varepsilon }_{0}}rE}{2}\] \[=\frac{1\times 2\times {{10}^{-2}}\times 7.182\times {{10}^{8}}}{2\times 9\times {{10}^{9}}}=7.98\times {{10}^{-4}}C/m\]


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