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Physics Honors - Magnetism

Terms in this set (31)

Magnetism
The force of attraction or repulsion of magnetic materials
what are the properties of magnets?
- Magnets attract iron and materials that contain iron.
- have domains
- have a north and a south side
- attract and repel (like charges repel, opposites attract)
magnetic pole
The ends of a magnetic object, where the magnetic force is strongest.
what makes something magnetic?
- Material must have magnetic domains
- things are magnetized from a change in domain
- electrons spin to make magnetism
magnetic domain
A region in which the magnetic fields of all atoms are lined up in the same direction
what are the characteristics of magnetic fields?
- exit the North and go into South
- circular
magnetic field
The area of magnetic force around a magnet
what destroys magnetism?
heat
what is the relationship between magnetic fields and electric currents?
magnetic fields can induce electric currents, and electric currents can induce magnetic fields
what is the right hand rule?
thumb = current direction
fingers = direction of magnetic force
magnetic flux
A measure of the strength of a magnetic field over a given area/ number of field lines.
Magnetic Flux Equation
Φ = BA cos θ
electromagnet
a coil that has a soft iron core and that acts as a magnet when an electric current is in the coil
the more loops in an electromagnet
the higher the field strength
Lorentz Force
the force a magnetic field exerts on a wire:

F = ILBsintheta
The Lorentz Force RHR
F = thumb
I = index
B = middle fingers
galvanometer
a device that uses an electromagnet to measure electric current
electric motors
A device that converts electrical energy to mechanical energy
how does an electric motor work?
they pass alternating current through opposing pairs of magnets to create a rotating magnetic field which creates a magnetic field in the motor's rotor, causing it to spin around
electric generator
a device that converts mechanical energy into electrical energy
Lorentz Force Equation (moving charge)
The force a magnetic field exerts on a moving charge can be found with:

F = qvBsintheta
Faraday's Law of Induction
if you move a loop of wire in a magnetic field, current will be induced in the wire
electromagnetic induction
the process of creating a current in a circuit by changing a magnetic field
induced electromotive force
the potential difference across a wire that results from the production of an electric field
EMF
the voltage induced on a wire moving in a magnetic field:

emf: BLVsintheta
What is the path of a charged particle in a magnetic field?
circular
second EMF equation
emf = N x change in magnetic flux/change in time
transformers
A device that increases or decreases the voltage of alternating current
AC/DC
Alternating current and direct current
equation for calculating voltages on each coil:
Vs/Vp = Ns/Np
What did Oersted discover?
the needle of a compass points in the direction of a current's flow
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