Class 12th Physics 2017 Set2 Delhi Board Paper Solution
An electron of mass me revolves around a nucleus of charge +Ze. Show that it behaves like a tiny magnetic dipole. Hence, prove that the magnetic moment associated with it is expressed as µ = − e / 2me L, where L is the orbital angular momentum of the electron. Give the significance of negative sign.
When electron revolves around a nucleus, it creates circular current around it. In this way, it is equivalent to a current carrying coil. So, it behaves as a tiny magnetic dipole.
We know that a current carrying coil behaves like a magnetic dipole having dipole moment equal to i A, where i is current and A is area of the coil.
where, e is charge of electron. Angular momentum of electron is, L =mr2ω
Substituting the above in equation. (i), we get
Here negative sign indicates µ is directs away from L.
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