question_answer

A proton, a deuteron and an \[\alpha -particle\] having the same kinetic energy are moving in circular trajectories in a constant magnetic field. If \[{{r}_{p}},\,\,{{r}_{d}}\,\,and\,\,{{r}_{\alpha }}\] denote respectively the radii of the trajectories of these particles, then-

A) \[{{r}_{\alpha }}=\,\,{{r}_{p}}\,\,<\,\,{{r}_{d}}\]                     

B) \[{{r}_{\alpha }}>{{r}_{d}}\,>\,\,{{r}_{p}}\]

C) \[{{r}_{\alpha }}=\,\,{{r}_{d}}\,\,>\,\,{{r}_{p}}\]                     

D) \[{{r}_{p}}=\,\,{{r}_{d}}\,\,>\,\,{{r}_{\alpha }}\]