A charged particle of mass $\mathrm{m}$ and charge $\mathrm{q}$ is projected into a uniform magnetic field of induction $\mathrm{B}$ with speed $\mathrm{v}$ which is perpendicular to $\mathrm{B}$ . The width of the magnetic field is $\mathrm{d}$ . The impulse imparted to the particle by the field is

$\left(\mathrm{d}\mathrm{ }<<\mathrm{ }\frac{\mathrm{m}\mathrm{v}}{\mathrm{q}\mathrm{B}}\right)$