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A uniformly charged ring of radius 3a and total charge q is placed in x‐y plane centred at origin. A point charge q is moving towards the ring along…

JEE Main 2019 — Physics Electromagnetism

2019mcqhard

A uniformly charged ring of radius 3a3a3a and total charge qqq is placed in x‐yx‐yx‐y plane centred at origin. A point charge qqq is moving towards the ring along the z−z-z− axis and has speed vvv at z=4az=4az=4a . The minimum value of vvv such that it crosses the origin is:

Official previous-year question

Held on 10 Apr 2019 · Verified 6 Jul 2026.

Options

  1. A

    2m(115q24πϵ0a)1/2\sqrt{\frac{2}{m}}{(\frac{1}{15}\frac{{q}^{2}}{4\pi {\epsilon }_{0}a})}^{1/2}m2​​(151​4πϵ0​aq2​)1/2

  2. B

    2m(415q24πϵ0a)1/2\sqrt{\frac{2}{m}}{(\frac{4}{15}\frac{{q}^{2}}{4\pi {\epsilon }_{0}a})}^{1/2}m2​​(154​4πϵ0​aq2​)1/2

  3. C

    2m(15q24πϵ0a)1/2\sqrt{\frac{2}{m}}{(\frac{1}{5}\frac{{q}^{2}}{4\pi {\epsilon }_{0}a})}^{1/2}m2​​(51​4πϵ0​aq2​)1/2

  4. D

    2m(215q24πϵ0a)1/2\sqrt{\frac{2}{m}}{(\frac{2}{15}\frac{{q}^{2}}{4\pi {\epsilon }_{0}a})}^{1/2}m2​​(152​4πϵ0​aq2​)1/2

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