Given, Charge of electron =e Mass of electron =me Orbital angular momentum of electron =L Let magnetic moment be µ. As we know that, µ= current (I)×Area(A) ⇒µ=
e
T
A . . . (i) where, e is charge of electron and T is time period. Since, T=
2πr
v
where, r is radius of track and v is speed of charge. ∵A=πr2 Substituting the value of T and A in Eq. (i), we get µ=
ev
2πr
⋅πr2=
evr
2
and L=mevr . . . (ii) where, L is angular momentum and me is mass of electron. ∴vr=