An electron , proton and an alpha particle having the same kinetic energy are moving in circular orbits of radii r(e) , r(p) , r(alpha) respectively ina uniform magnetic field B. The relation between r(e),r(p),r(alpha) is :
(1) r(e) > r(p) = r(alpha)
(2) r(e) < r(p) =r(alpha)
(3) r(e) < r(p) < r(alpha)
(4) r(e) < r(alpha) < r(p)
