Magnetic Fields are created by permanent magnets and moving charges.
*magnetic field lines depict the direction a compass needle would point if placed in the field from the North Pole to the South Pole
SI units = Tesla (T) = N*s/m*C
1 T = 104 gauss
Magnetic Materials:
1. Diamagnetic
materials made of atoms with no unpaired electrons and that have no net magnetic field.
*weakly antimagnetic
Magnetic Materials:
2. Paramagnetic
materials have unpaired electrons and have a net magnetic dipole, but the atoms in these materials are usually randomly oriented so that the material itself creates no magnetic field.
*weakly magnetized in the presence of an external magnetic field.
Magnetic Materials:
3. Ferromagnetic
materials have unpaired electrons and permanent atomic magnetic dipoles that are normally oriented randomly so that the material has no net magnetic dipole.
*will become strongly magnetized when exposed to a magnetic field or under certain temperatures.
*Curie Temperature:
above = paramagnetic
below = permanently magnetized
Force on a MovingCharge
A charge moving in a magnetic field experieces a force exerted on it.
q = charge (+/-)
v = velocity
B = Magnetic Field
*the magnetic force is zero when a charge moves parallel or antiparallel to the magnetic field
*@ sin(900): F = qvB = mv
Right-Hand Rule for Finding Direction of Force
*Note that the right-hand Rule gives the direction of magnetic force exerted on a proton.
The direction of force on an electron is simply the opposite direction of the force on a proton.
Force on a Current-Carrying Wire
F = iLBsinθ
x --> represents B fields pointing into the page.
* --> represents B fields pointing out of the page.
Center of Wire Loop - Magnetic Force
Around a Straight Wire - Magnetic Force
Right-Hand Rule for Direction of B Field produced by Current-Carrying Wires
*right thumb points in the direction of current flow.
*Wrap your fingers around the wire as if you were grabbing it with your palm
*The direction that the fingers curl is the direction of the magnetic field.
Wave Superposition
*Waves can also be shifted with respect to one another by other fractions of a cycle, such as λ or 90o out of phase.