Right-hand Rule for a Moving Proton
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First, rotate your right wrist so you can point your fingers in the direction of the proton's velocity (green vector).
Second, curl your fingers toward the unit vector r-hat (purple vector pointing from source to observation location).
Third, stick out your thumb in the direction of the magnetic field at the observation location.
Fourth, move your thumb to the observation location (if your own thumb is not detachable you may choose only to imagine this step).