dirac-quant.md

Dirac Quantization Condition

To calculate the angular momentum generated by a pair of electric-magnetic charge with distance d, let's put the magnetic charge at origin and electric charge at (0, d, 0), then look at B and E at point P on plane xOy:

The momentum density at P is:

The total angular momentum around axis y is: ^[1]

Let's assume the angular momentum meets n multiples of , then we get the Dirac quantization condition:

i.e.

Note

1. Here is the calculation for the integral (2/d); here is the numeric verification.