A uniformly charged ring of radius $3a$ and total charge $q$ is placed in $xy-$ plane centered at origin. A point charge $q$ is moving towards the ring along the $z-$ axis and has speed $v$ at $z = 4a$. The minimum value of $v$ such that it crosses the origin is
A uniformly charged ring of radius $3a$ and total charge $q$ is placed in $xy-$ plane centered at origin. A point charge $q$ is moving towards the ring along the $z-$ axis and has speed $v$ at $z = 4a$. The minimum value of $v$ such that it crosses the origin is
- [JEE MAIN 2019]
- A
$\sqrt {\frac{2}{m}} {\left( {\frac{1}{5}\frac{{{q^2}}}{{4\pi { \in _0}a}}} \right)^{1/2}}$
- B
$\sqrt {\frac{2}{m}} {\left( {\frac{1}{15}\frac{{{q^2}}}{{4\pi { \in _0}a}}} \right)^{1/2}}$
- C
$\sqrt {\frac{2}{m}} {\left( {\frac{4}{15}\frac{{{q^2}}}{{4\pi { \in _0}a}}} \right)^{1/2}}$
- D
$\sqrt {\frac{2}{m}} {\left( {\frac{2}{15}\frac{{{q^2}}}{{4\pi { \in _0}a}}} \right)^{1/2}}$
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