The correct option (c) (r1/r2)2
Explanation:
Magnetic Force = qVB
centripetal force = (mV2/r)
∴ [(mV2)/r] = qVB
∴ r = (mV/qB)
i.e. mV = qrB (1)
also assuming particle starts from rest, final kinetic energy = work done on each particle
∴ (1/2)m1v12 = q ∙ V
and (1/2)m2v22 = q ∙ V
∴ m1V12 = m2V22 (2)
from (1), m1V1 = qBr1 & m2V2 = qBr2
∴ from (2), m1[(qBr1)/m1]2 = m2 [(qBr2)/m2]2
∴ (r12/m1) = (r22/m2) hence (m1/m2) = (r1/r2)2