Problem 3.386

A non-relativistic charged particle flies through the electric field of a cylindrical capacitor and gets into a uniform transverse magnetic field with induction $B$ (Fig. 3.100 ). In the capacitor the particle moves along the arc of a circle, in the magnetic field, along a semi-circle of radius $r$. The potential difference applied to the capacitor is equal to $V,$ the radii of the electrodes are equal to $a$ and $b$, with $a < b$. Find the velocity of the particle and its specific charge $q / m$