$A$ particle of charge $-q$ and mass $m$ moves in a circle of radius $r$ around an infinitely long line charge of linear density $+\lambda$. Then the time period will be given as (Consider $k$ as Coulomb's constant).

• A
  $T^2=\frac{4 \pi^2 m}{2 k \lambda q} r^3$
• B
  $T=2 \pi r \sqrt{\frac{m}{2 k \lambda q}}$
• C
  $T=\frac{1}{2 \pi r} \sqrt{\frac{m}{2 k \lambda q}}$
• D
  $T=\frac{1}{2 \pi} \sqrt{\frac{2 k \lambda q}{m}}$