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  • Stuck here, help me understand: A point charge Q is located on the axis of disc at a distance b from the plane of the disc. Calculate R if one fourth of the electric flux from the charge passes throughout the disc.

A point charge Q is located on the axis of disc at a distance b from the plane of the disc. Calculate R if one fourth of the electric flux from the charge passes throughout the disc.

  • Option 1)

    \sqrt{3}b

  • Option 2)

    \sqrt{3}

  • Option 3)

    \frac{b}{\sqrt{3}}

  • Option 4)

    b^{2}\sqrt{3}

 

Answers (1)

best_answer

As we learnt ,

 

If r = R for both cylinder -

E_{surface}=\frac{\lambda }{2\lambda \varepsilon _{0}R}

V_{surface}=\frac{-\lambda }{2\lambda \varepsilon _{0}}\log_{e}R+c

 

- wherein

\lambda - Linear charge density.

 

 

 

\phi =\frac{(1-cos \theta)Q }{2\epsilon _{o}}

\phi =\phi_{total} \frac{(1-cos \theta) }{2} \Rightarrow \phi = \frac{1}{4}\phi_{T}

\theta = 60^{o}

\frac{R}{b}= tan \theta = \sqrt{3}

R = \sqrt{3}b

 


Option 1)

\sqrt{3}b

Option 2)

\sqrt{3}

Option 3)

\frac{b}{\sqrt{3}}

Option 4)

b^{2}\sqrt{3}

Posted by

Plabita

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