Magnets
There are three types of magnetic materials: Ferromagnetic, paramagnetic and diamagnetic.
Ferromagnetic: When exposed to an external magnetic field, the domains in a ferromagnetic material align in the direction of the field and the material becomes magnetized. Ferromagnetic materials can stay magnetized after the external field is removed.
Paramagnetic: Just like ferromagnetic materials, paramagnetic magnetic material's domains also align in the direction of an external magnetic field. However once the field is removed, paramagnetic materials do not stay magnetized.
Diamagnetic: A Diamagnetic material's poles align in the opposite direction of an external magnetic field and therefore a diamagnetic material always repels any magnet brought near.
Induction
Induced Current: A changing external magnetic field acting on a conductive object will induce a current within the object.
Induced Magnetic Field: A flow of charged particles will induce a magnetic field in the environment.
Electric Field (E)
Positive charges move in the direction of an Electric Field and negative charges move in the opposite direction of an Electric Field.
Faraday's Law
The induced electric field in a closed circuit is equal to the negative of the rate of change of magnetic flux through the circuit.
magnetic flux: The "amount" of magnetic field passing through a cross-sectional area
Magnetic Field (B)
Lenz's Law
The current induced in a closed circuit due to a varying external magnetic field will itself induce a magnetic field that opposes the change in the external magnetic field.
Current
Lorentz Force
A charged particle moving with velocity v through a uniform magnetic field will experience a force equivalent to F = qv x B (qvBsin(θ)) where q is the charge of the particle
Potential Energy and Energy Wells
Potential energy is the energy stored by an object due to its position within a force field. For example, lifting an object up off the ground to a height h will give it a potential energy of mass*g*h where g = acceleration due to gravity.
Objects do not like having energy and find ways to spend it. If moving an object a direction along an axis raises its potential energy, then the object will remain at the point that gives it the lowest energy possible. The object is said to be in an energy well.
