Question bank/JEE Advanced/Physics

An $\alpha$-particle (mass 4 amu) and a singly charged sulfur ion (mass 32 amu) are initially at rest. They are accelerated through a potential $V$ and then allowed to pass into a region of uniform magnetic field which is normal to the velocities of the particles. Within this region, the $\alpha$-particle and the sulfur ion move in circular orbits of radii $r_{\alpha}$ and $r_{S}$, respectively. What is the ratio $\left(r_{S} / r_{\alpha}\right)$?

Source: JEEBench (IIT Delhi) / JEE Adv 2021 Paper 1