BCECE Medical BCECE Medical Solved Papers-2008

  • question_answer
    If the electric flux entering and leaving an enclosed surface respectively are \[{{\phi }_{1}}\] and \[{{\phi }_{2}}\], the electric charge inside the surface will be

    A)  \[\frac{{{\phi }_{2}}-{{\phi }_{1}}}{{{\varepsilon }_{0}}}\]

    B)  \[\frac{{{\phi }_{1}}+{{\phi }_{2}}}{{{\varepsilon }_{0}}}\]

    C)  \[\frac{{{\phi }_{1}}-{{\phi }_{2}}}{{{\varepsilon }_{0}}}\]

    D)  \[{{\varepsilon }_{0}}\,({{\phi }_{1}}+{{\phi }_{2}})\]

    Correct Answer: D

    Solution :

    According to this law, the net electric flux through any closed surface is equal to the net charge inside the surface divided by\[{{\varepsilon }_{0}}\]. Therefore,                 \[\phi =\frac{q}{{{\varepsilon }_{0}}}\] Let \[-{{q}_{1}}\] be the charge, due to which flux \[{{\phi }_{1}}\] is entering the surface \[\therefore \] \[{{\phi }_{1}}=\frac{-{{q}_{1}}}{{{\varepsilon }_{0}}}\] Let \[+{{q}_{2}}\] be the charge, due to which flux \[{{\phi }_{2}}\]  is leaving the surface \[\therefore \] \[{{\phi }_{2}}=\frac{{{q}_{2}}}{{{\varepsilon }_{0}}}\] or            \[{{q}_{2}}={{\varepsilon }_{0}}{{\phi }_{2}}\] So, electric charge inside the surface                 \[={{q}_{2}}-{{q}_{1}}\]                 \[={{\varepsilon }_{0}}\,{{\phi }_{2}}+{{\varepsilon }_{0}}\,\,{{\phi }_{1}}\] \[={{\varepsilon }_{0}}\,({{\phi }_{2}}+\,\,{{\phi }_{1}})\]


You need to login to perform this action.
You will be redirected in 3 sec spinner