A proton and a deuteron, each moving with velocity `vecv`, enter simultaneously in the region of magnetic field `vecB` acting normal to the direction of velocity. Trace their trajectories establishing the relationship between the two .

Explanation

We know that when a particle of mass .m. and charge .q. moving with a velocity `vecv` enters a region of magnetic field `vecB` acting normal to the direction of velocity, it describes a circular path of radius `r = (mv)/(qB)`.
As per question `v_("proton") = v_("deuteron")` and charges are also same.
But `m_("deuteron") = 2m_("proton") `. As a result, `r_("deuteron") = 2r_("proton")`
The trajectories have been traced in fig.