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Grade 12Electrostatics

Consider a circular ring of radius 'r' uniformly charged with a linear charge density lemda .Find the electric potential at a point on the axis at a distance x from the centre of the ring .Using this expression for the potential, find the electric field at this poi

Profile image of Tanmay kumar
7 Years agoGrade 12
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1 Answer

Profile image of Eshan
7 Years ago
Dear student,

Distance of each infinitesimally small charge element on the ring from the given point is

d=\sqrt{x^2+r^2}
Hence total electric potential at that point=V=\dfrac{1}{4\pi\epsilon_0}\dfrac{\int dq}{\sqrt{x^2+r^2}}=\dfrac{1}{4\pi\epsilon_0}\dfrac{\lambda( 2\pi r)}{\sqrt{x^2+r^2}}=\dfrac{\lambda r}{2\epsilon_0\sqrt{x^2+r^2}}
HenceE=-\dfrac{dV}{dx}=\dfrac{1}{2}\dfrac{\lambda r}{2\epsilon_0 (x^2+r^2)^{3/2}}.2x=\dfrac{\lambda rx}{2\epsilon_0(x^2+r^2)^{3/2}}