BHU PMT BHU PMT (Screening) Solved Paper-2007

  • question_answer
    A charge q is located at the centre of a cube. The electric flux through any face is

    A)  \[\frac{\pi q}{6(4\pi {{\varepsilon }_{0}})}\]                       

    B)  \[\frac{q}{6(4\pi {{\varepsilon }_{0}})}\]

    C)  \[\frac{2\pi q}{6(4\pi {{\varepsilon }_{0}})}\]                     

    D) \[\frac{4\pi q}{6(4\pi {{\varepsilon }_{0}})}\]

    Correct Answer: D

    Solution :

                     Key Idea: Gauss's law states that, "the net electric flux through any closed surface is equal to the net charge inside the closed surface divided by\[{{\varepsilon }_{0}}''.\] From Gauss's law                 \[\phi =\frac{q}{{{\varepsilon }_{0}}}\] This is the net flux coming out of the cube. Since, a cube has 6 sides so electric flux through any face is                 \[\phi '=\frac{\phi }{6}=\frac{q}{6{{\varepsilon }_{0}}}=\frac{4\pi q}{6(4\pi {{\varepsilon }_{0}})}\]


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