# Physics: week 27

This week in the Ron Paul Curriculum physics course was an intro to the interplay between electricity and magnetism, and AC circuits.

Electromagnetic induction:

Just as a magnetic field exerts a force on a current carrying wire, making it want to move, if we move a wire through a magnetic field, it creates an electric current.  This is electromagnetic induction.  Current is produced if you move the conductor or the magnetic field.

Magnetic flux:

Magnetic field times the unit area perpendicular to the field.

If the flux through N loops of wire changes by an amount of delta Fee during a time of delta T the average emf is:

Lenz’s law:

An induced emf always gives rise to a current whose magnetic field opposes the original change in flux.

Two ways to change flux:

• Change magnetic field
• Change the area that is perpendicular to it.

EMF induced in a moving conductor:

Changing magnetic flux produces an electric field:

Field induction:

• An electric field is induces in any region of space in which a magnetic field is changing with time.
• A magnetic field is induced in any region of space in which an electric field is changing with time.