Let Fp,Fd and Fα be the forces and vp,vd and vα be the velocities of proton, deuteron and α−particle, respectively. Since, F=Bqv On dividing and multiplying F by m, we get F=Bqv
m
m
⇒F=B
q
m
p(∵p=mv) ⇒F∝q∕m(∵p and B are same) ∴Fp:Fd:Fα=
+q
m
:
+q
2m
:
+2q
4m
=1:1∕2:1∕2=2:1:1 and =Bqv ⇒∝F∕q ∴vp:vd:vα=