A Proton and an Alpha particle are accelerated through the same potential difference enter in a region of uniform magnetic field with their velocities perpendicular to the field they also have same Kinetic energy. compare the radii of circular path followed by them
we know that
mv2/r = qvB
The radius of the cirxular path is given as
r = mv/qB
now as E = (1/2)mv2
we have, mv = (2mE)1/2
so, the radius will be
r = √(2mE)/qB
or
the radius of proton
rp = √(2mpE) / qpB
the radius of an alpha particle
ra = √(2maE) / qaB
we also know that
mp = 4ma
and
qp = 2qa
so, the ratios would be
rp : ra = 1 : 1