Q. In the figure shown, a charge q moving with a velocity v along the x-axis enter into a region of uniform magnetic field. The minimum value of v so that the charge q is able to enter the region x > b
(a) $ \displaystyle \frac{q B b}{m}$
(b) $ \displaystyle \frac{q B a}{m}$
(c) $ \displaystyle \frac{q B( b -a )}{m}$
(d) $ \displaystyle \frac{q B( b +a )}{2m}$
Ans: (c)
Sol: If particle enter the region x > b
Then , R ≥ (b-a)