A particle of mass m and charge q moves with a constant velocity v along the positive x− direction.

extending from $x=a$ to $x=b$. The minimum value of $v$ required so that the particle can just enter the region $x>b$ is

Answer:- Correct option is B)

Radius of curvature has to be better than the width of magnetic field for the particle to enter the region x>B.

∴qBmv​>(b−a)

⇒v>mqB(b−a)​

∴vmin​=mqB(b−a)​