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Ten charges are placed on the circumference of a circle of radius R with constant angular separation between successive charges. Alternate…

JEE Main 2020 — Physics Electromagnetism

2020mcqmedium

Ten charges are placed on the circumference of a circle of radius R with constant angular separation between successive charges. Alternate charges1,3,5,7,91,3,5,7,91,3,5,7,9 have charge (+q)(+q)(+q) each, while 2,4,6,8,102,4,6,8,102,4,6,8,10 have charge (–q)(–q)(–q) each. The potential V and the electric field E at the centre of the circle are respectively : (TakeV=0V=0V=0 at infinity)

Official previous-year question

Held on 5 Sept 2020 · Verified 6 Jul 2026.

Options

  1. A

    V=10q4πϵ0R;E=0V=\frac{10q}{4\pi {\epsilon }_{0}R};E=0V=4πϵ0​R10q​;E=0

  2. B

    V=0,E=10q4πϵ0R2V=0,E=\frac{10q}{4\pi {\epsilon }_{0}{R}^{2}}V=0,E=4πϵ0​R210q​

  3. C

    V=0;E=0V=0;E=0V=0;E=0

  4. D

    V=10q4πϵ0R;E=10q4πϵ0R2V=\frac{10q}{4\pi {\epsilon }_{0}R};E=\frac{10q}{4\pi {\epsilon }_{0}{R}^{2}}V=4πϵ0​R10q​;E=4πϵ0​R210q​

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