# Biot–Savart law: the origin of chirality?

by carrz
Tags: biot–savart, chirality, origin
 PF Gold P: 1,141 The right-hand rule works because it gives the same direction as the vector product in the Biot-Savart law: $$\mathbf j(\mathbf x') \times |\mathbf x - \mathbf x'|$$ where ##\mathbf j## is current density at point ##\mathbf x'##, ##\mathbf x## is point where the magnetic field is sought. The vector product chooses one direction for ##\mathbf B## from two possibilities. Direction of magnetic field could have been defined to be opposite. Then we would use left hand to get this opposite direction.