A circular lamina of radius 'R' is having surface charge density $σ\, cm^{-2}$. Electric field at axial distance $'2R'$ is
Answer & explanation
Correct answer: option 1
The correct answer is option (1) : $E=\frac{σ}{2\epsilon_0}\left(1-\frac{2}{\sqrt{5}}\right)$
$E=\frac{σ}{2\epsilon_0}(1-cos \phi )$, where $cos \phi =\frac{2R}{\sqrt{4R^2+R^2}}$
$E=\frac{σ}{2\epsilon_0}\left(1-\frac{2}{\sqrt{5}}\right)$
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