Magnetism Review Page One

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Magnetism Review Page One

• The amount of magnetic lines of force in a given
  or measured area is known as flux ___________.
• The unit of flux density measured in maxwells per
  square centimeter is the _________.
• The unit of flux density measured in webers per
  square meter is the _________.
• The ability of a material to conduct, or
  concentrate magnetic flux as compared to air or a
  vacuum is known as ____.
• The two units of magnetic flux are the _________
  which is a smaller unit compared to the weber.
• _____________ is the ability of a material to
  hold magnetism after the magnetic field is
  removed from the material.
• The distance between the north pole and the south
  pole of a magnet is called the air _____.
• One group of magnetic materials consisting of
  nickel, cobalt and iron that have a very high
  permeability, and flux density is called a
  __________ material.

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Magnetism Review Page Two

• The symbol for flux density is the letter
  ________.
• The _______ is the magnetic quantity that refers
  to the field strength or intensity of an
  electromagnet and is represented by the symbol H.
• A ________ is an electromagnet produced from a
  coil carrying a current through it.
• A 200 turn coil carrying 4 amperes of current
  produces a magnetomotiveforce, mmf, of _____
  ampere-turns.
• ________ or the opposition to the flow of
  magnetic lines of force is similar to resistance
  in electrical circuits.
• Magnetic flux are magnetic lines of force, and
  can be increased in an electromagnetic, by
  increasing either the number of turns or the
  _______ carried in a coil.
• All magnetic fields are at a ______ degree angle
  with respect to the current flowing through a
  conductor.
• It is desirable for a core to have a ___
  permeability and a low retentivity.

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Magnetism Review Page Three

• Hysteresis is caused by core __________ and
  retentivity, and acts as a power loss in
  electromagnetic circuits.
• For transformers to operate, the electric current
  flowing through the wire must be ______ or
  pulsating DC electricity.
• Because ________ is generated when charges or
  electrons are in motion, most of the planets in
  our solar system have a magnetic field.
• The magnetic field around the Earth protects our
  environment from harmful ______ rays and other
  high-speed radiation that comes from space.
• The magnetic field of the Earth is _______ and
  due to this phenomenon requires that navigation
  maps updated regularly.
• The shape of read/write head of computer disk
  drive is similar to a ________ magnet, and allows
  a magnetic field to be concentrated.
• Magnetomotive force, mmf in magnetic circuits is
  similar to _______ in electrical circuits.
• The direction of the magnetic field of the sun
  changes every _______ years.

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Magnetism Review Page Four

• Two wires with current traveling in the same
  direction are ________ each other because the
  magnetic fields in the wire rotate in opposite
  directions.
• The direction of magnetic lines of force is
  considered to take an external path from the
  ________ pole to the_________ pole of a magnet.
• When two magnets are brought near each other,
  unlike poles will be ___________ to each other.
• When two magnets are brought near each other,
  like poles will be _________ to each other.
• Two wires which have current flowing in the
  opposite direction are ________ each other
  because the magnetic fields in the wire rotate in
  the same directions.
• The transfer of magnetism from one magnetic
  material to another is called magnetic
  ____________.
• The total number of magnetic lines of force or
  maxwells is known as magnetic _____.

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Magnetism Review Page Five

• Magnetic __________ in a material occurs when an
  increase of magnetizing force produces no further
  increase in the magnetic field.
• All magnetic fields generated by electrical
  current flow are ________, and have the greatest
  intensity closest to the wire.
• _____ voltage can be induced in a wire, if the
  wire cuts a magnetic field at a 90 degree angle.
• _________ magnets have a high flux density
  because they have a closed path and no air gap.
• In order to induce a voltage in a wire the
  current must be ________ directions at all times.
• The units of maxwells per square centimeters are
  called _____.
• The units of webers per square meter are called
  _______.
• The sign used on magnetic field diagrams means
  that the current is flowing ____ the paper.
• The lagging behind of magnetic lines of force
  after a magnetizing force is applied is
  __________.

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Magnetism Review Page Six

• One group of magnetic materials consisting of
  gold, silver, and copper that have a low
  permeability, and align opposite of that of the
  applied magnetic field is called a __________
  material.
• ________ law predicts the amount of induced
  voltage in a coil based on the number of turns,
  change in flux, and rate of time change.
• If the direction of current in a coil reverses,
  the _______ of the electromagnetic field also
  reverses.
• The temperature at which a magnetic material will
  lose its magnetism is called the _______
  temperature.
• In an electromagnetic circuit, the magnetomotive
  force is equal to the number of turns in a coil
  time the _______
• The opposition or resistance to magnetic flux in
  a magnetic circuit is __________ and is
  represented by the symbol R.
• One group of magnetic materials consisting of
  aluminum and palladium that have a low
  permeability, and align weakly to an applied
  magnetic field is called a __________ material.