Magnetic field

The laws of Faraday and Lenz

The visual on the left shows Faraday's experiment in a qualitative way: you can see a magnet, with its lines of force, and a circuit formed by a coil and a light bulb, without a power supply.

If we move the magnet through the coil or away from it (dragging the dot in the middle) the bulb will light up. It is the variation of the mangetic flux through the coil that generates a current through the light bulb. This current is known as an induced current.

You can study the production of induced currents in more detail by clicking on . In this visual, you will be able to study the induced current in a simple circuit when the surface of the circuit is changed and when the field intensity is altered. You will also learn the laws of Faraday and Lenz, which can be summarised in the following expression:

where emf is the induced electromotive force.

In the section on alternating current you will find how an induced current is produced when the angle between the field vector and the surface of the circuit changes.

	Natural magnets
	Lines of force
	Magnets and currents
	Conclusions

	on a charged particle
	on a straight cable
	on a loop
	Conclusions

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

	Magnetic flux
	The laws of Faraday and Lenz
	Self-induction
	Conclusions

	The generation of alternating currents
	A circuit of alternating current
	Conclusions