The correct option is A π150 s
q=−1 C; m=0.2 g; r=1 m; λ=+1 nC/m
Let v be the speed of particle moving in the circle.
Here, the electric force (Fe) acting on charge −1 C due to infinite line charge will act as the required centripetal force.
⇒q×2kλr=mω2r [∵ E=2kλr]
Now, time period, T=2πω
Hence, option (a) is correct.