Magnetic field

Conclusions about the creation of magnetic fields

	A rectilinear current or a moving charge create lines of force around themselves as shown in the figure on the left. The modulus of the field created by a rectilinear current of an indefinite length is given by the following formula:
where I is the intensity of the current and r is the distance to the point at which the intensity is equal to B, μ is the magnetic permeability of the medium.
	Two parallel rectilinear currents interact in such a way that they attract each other if they are flowing in the same direction and they repel each other if they are flowing in opposite directions. The value of this force per unit length is: where r is the distance between the conductors, I1 and I2 are the corresponding intensities of the current and μ is the magnetic permeability of the medium. Click on next to read more conclusions.

	by a charged particle
	by a rectilinear current
	by a coil
	An explanation of natural magnetism
	Conclusions

	The generation of alternating currents
	A circuit of alternating current
	Conclusions