NEET Sample Paper NEET Sample Test Paper-82

  • question_answer
    The electric potential V at any point (x, y, z) in space is given according to relation\[\operatorname{V} = 2{{x}^{2}}V\]. The electric field intensity at the point (2m, 0, 2m) will be

    A)  \[-\text{ }4\text{ }V{{m}^{-}}^{1}\]              

    B)  \[+\,4\text{ }V{{m}^{-}}^{1}\]

    C)  \[-\,8\text{ }V{{m}^{-}}^{1}\]                      

    D)  \[8\text{ }V{{m}^{-}}^{1}\]

    Correct Answer: C

    Solution :

    As,       \[\operatorname{V}=2{{x}^{2}}\] \[\therefore \,\,\,\,\,\,\,{{E}_{x}}=\frac{-\partial V}{\partial x}=-\frac{\partial {{(2x)}^{2}}}{\partial x}=-\,4x\] \[{{E}_{Y}}=\,\,\frac{-\partial V}{\partial y}=0,\,\,{{E}_{Z}}=\frac{-\,\partial \,{{V}^{2}}}{\partial z}\,\,=\,\,0\] \[\therefore \,\,\,\,{{E}_{net}}={{E}_{x}}=-\,4x\] At, \[\left( 2m, 0,\,\,2m \right)\] \[{{E}_{net}}\,\,=\,\,(-\,4)\times 2\,\,=\,\,-8V{{m}^{-\,1}}\]


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