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NEET Sample Paper NEET Sample Test Paper-89

  • question_answer
    The magnitude of the average electric field normally present in the atmosphere just above the surface of the Earth is about 150 N/C, directed inward towards the center of the Earth. This gives the total net surface charge carried by the Earth to be: [Given\[{{\varepsilon }_{0}}=8.85\times {{10}^{-12}}{{C}^{2}}/N-{{m}^{2}},\]\[{{R}_{E}}=6.37\times {{10}^{6}}m\]]

    A) \[+670\,\,kC\]   

    B)        \[-670\,\,kC\]

    C) \[-680\,\,kC\]     

    D)        \[+680\,\,kC\]

    Correct Answer: C

    Solution :

    [c] Given, Electric field E=150 N/C Total surface charge carried by earth q =? or, \[q={{\in }_{0}}\]E A \[={{\in }_{0}}E\,\pi \,{{r}^{2}}.\] \[=8.85\times {{10}^{-12}}\times 150\times {{(6.37\times {{10}^{6}})}^{2}}.\] \[\simeq 680\,KC\] As electric field directed inward hence \[q=-680\,kC\]


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