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Chapters 24,25, and 26
N/A
39
Physics
11th Grade
04/28/2011

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Term
lodestone
Definition
naturally occuring magnetic rocks
Term
when is a magnet polarized
Definition
when it has a north and south pole
Term
ferromagnetic
Definition
materials that can be converted into a magnet
Term
where do magnetic fields exist
Definition
in areas with magnetic force
Term
magnetic flux
Definition
the number of magnetic field lines passing through a surface
Term
where is a magnetic field strongest
Definition
at the poles
Term
where do magnetic field lines leave
Definition
the north pole
Term
where do magnetic field lines enter
Definition
the south pole
Term
current carrying wires produce a
Definition
magnetic pole perpendicular to the direction of the current
Term
first right hand rule
Definition
the direction of the current is the direction of the magnetic field
Term
solenoid
Definition
a long coiled wire which increases total strength
Term
domain
Definition
the alignment of electrons of multiple atoms in a group of atoms
Term
when does a material become a magnet
Definition
when domains align
Term
what does a motor convert
Definition
electrical energy to kinetic energy
Term
galvanometer
Definition
a device used to measure small currents
Term
a changing magnetic field can produce a
Definition
current
Term
electromagnetic induction
Definition
the process of generating a current through a circuit
Term
electromotive force
Definition
the influence that makes the current flow from higher to lower potential difference
Term
electric generator
Definition
consists of a number of wire loops around an iron core that rotates between a north and south pole of a magnet
Term
armature
Definition
the wire coil of an electric motor
Term
in the U.S. utilities use a frequency of
Definition
60Hz
Term
In the U.S. we use a voltage of
Definition
120V
Term
Lenz's law predicts
Definition
the direction of current flow
Term
Lenz's states that
Definition
An induced current is always in such a direction as to oppose the motion or change causing it
Term
Lenz's law causes the armature of a generator to be
Definition
more difficult to turn
Term
sensitive balance
Definition
uses lenz's law to stop oscillation
Term
eddy currents
Definition
generated in a metal and produces a magnetic field that acts to oppose the motion that caused the current
Term
self inductance
Definition
the induction of emf in a wire carrying changing current
Term
In the changing current due to self inductance a back-emf is created which makes the potential of the top of the wire
Definition
more negative than the bottom of the wire
Term
transformers
Definition
devices that use self inductance to increase or decrease AC voltages
Term
what did JJ Thompson discover?
Definition
the charge to mass ratio of an electron
Term
isotope
Definition
differing forms of an atom which have different masses but the same chemical properties
Term
mass spectrometer
Definition
a device used to determine the charge of mass ratios of certain ions
Term
a changing electric field produces a changing magnetic field
Definition
electric charges aren't necessary
Term
elecrtomagnetic wave
Definition
a combined electric and magnetic field that travels through space at right angles to one another
Term
dielectric
Definition
a nonconducting material
Term
piezoelectricity
Definition
the application of AC voltage onto a section of quartz crystal which results in sustained oscillations
Term
x-rays
Definition
high frequency Em waves that are created when high energy electrons strike the metal target inside a cathode ray tube
Term
right hand rule
Definition
the direction of a magnetic force on a moving charge is always perpendicular to the magnetic field and the velocity of the charge
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