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JEE Main 20252 AprilEvening Shift
Exam
JEE Main
Year
2025
Date
2 April
Shift
Evening Shift
Subject
Physics
Chapter
Electrostatics

JEE Main 2025 · 2 April · Evening Shift · Physics · Electrostatics

Consider a circular loop that is uniformly charged and has a radius...

Consider a circular loop that is uniformly charged and has a radius a2\mathrm{a} \sqrt{2}. Find the position along the positive z -axis of the cartesian coordinate system where the electric field is maximum if the ring was assumed to be placed in xy-plane at the origin :

Options

  1. Aa2\frac{a}{\sqrt{2}}
  2. Ba2\frac{a}{2}
  3. Ca
  4. D0

Correct answer

C. a

Step-by-step solution

E=KQr(x2+R2)3/2dEdx=0∴x=R2=2a2=a\begin{aligned} & \mathrm{E}=\frac{\mathrm{KQr}}{\left(\mathrm{x}^2+\mathrm{R}^2\right)^{3 / 2}} \\ & \frac{\mathrm{dE}}{\mathrm{dx}}=0 \\ & \therefore \mathrm{x}=\frac{\mathrm{R}}{\sqrt{2}}=\frac{\sqrt{2} \mathrm{a}}{\sqrt{2}}=\mathrm{a}\end{aligned}
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