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45 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Using the left hand rule for coils, the thumb points in the direction of.... |
The flux lines or the north pole of the coil |
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As the current in a conductor is increased, what happens to the magnetic lines of force surrounding the conductor? |
More lines of flux are formed and forced outward |
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Is it true that any time a charge moves, there must be a magnetic field set up around that charge? |
Yes |
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As the direction of current in a conductor is reversed, what happens to compasses surrounding the conductor? |
The compasses reverse direction as well |
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As the current in a conductor is decreased, what happens to the magnetic lines of force surrounding the conductor? |
The lines of force collapse inward |
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Materials that act in a way similar to iron ina magnetic field are referred to as ________ materials |
Ferromagnetic Materials |
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Another name for magnetic lines of force? |
Magnetic flux |
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Opposite of Reluctance |
Permeability |
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B is ______ |
Flux density |
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H is |
Magnetizing Force |
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ų is _______ |
Permeability |
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mmf is ______ |
Magnetomotive force |
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The spreading out of flux lines in an air gap is referred to as _________ |
Fringing |
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The term for the lag of flux density behind magnetizing intensity is _________ |
Hysteresis |
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The ease with which flux is set up in a unit length and cross-section of a material is referred to as the __________ |
Permeability |
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Magnetic cores that are constructed of alternating layers of magnetic material and electrical insulator are said to be.... |
Laminated |
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Opposition to the formation of flux lines in a magnetic circuit is called..... |
Reluctance |
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The amount of reverse magnetizing force required to remove the residual magnetism is called the.... |
Coercive force |
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The type of core material used for lifting electromagnets would have a _______ retentivity |
Low |
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Magnetic cores are usually constructed from materials with a high _____ and a low _____ |
Permeability, Reluctance |
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The amount of energy lost due to the constant reversals of the magnetic field in AC circuits is referred to as _______ loss |
Hysteresis |
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Residual Magnetism is a measure of the amount of _______ remaining in the magnetic material after the magnetizing force has been removed. |
Flux density |
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The magnetic flux in a circuit is directly proportional to the _____ and inversely proportional to the _____ of the magnetic circuit |
MMF, Reluctance |
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A helically wound coil that produces a strong magnetic field |
Solenoid |
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Is the field around the conductor more or less dense closer to the conductor? |
More dense |
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Amount of flux density remaining in the magnetic material after the magnetizing force is removed |
Residual Magnetism |
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Unit for Magnetic Flux (# of flux lines) |
Weber or Wb |
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Formula for Magnitude |
Fm = (k×I1×I2) ÷ d^2 |
Directly proportional to the currents flowing and inversely proportional to the distance between conductors |
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Most practical way to vary the strength of an electromagnet? |
Vary the current through the coil |
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Metals that can be magnetized but not as easily as ferromagnetic materials |
Paramagnetic metals |
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A point where magnetic flux is more dense |
Magnetic pole |
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Metal or non metal materials that cannot be magnetized |
Diamagnetic |
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The point where all of the domains in the magnetic material have aligned themselves with the magnetic field |
Theoretical saturation |
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The force that causes the setting up of flux lines in a magnetic circuit |
Magnetomotive force (mmf) |
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Maximum amount of magnetic flux a material can hold |
Saturated |
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Magnetizing force necessary to reduce the flux density in a magnetic material to zero |
Coersive force |
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The region in which a magnetic material is acted upon by a magnetic force |
Magnetic field |
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When it is no longer practical to try to increase flux density |
Practical saturation |
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The same thing as retentivity |
Residual magnetism |
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A materials ability to retain magnetism after the magnetizing force has been removed |
Retentivity |
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The path along which the flux lines follow as they form their complete loops |
Magnetic circuit |
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The amount of flux per unit cross section of a magnetic circuit |
Flux density |
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To deflect the lines of force around the object you are trying to protect |
Screen |
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The most practical way to vary the strength of an electromagnet is to vary the... |
Current |
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Current is moving through a wire. If more current passes through the wire, then the new flux lines will form at _____ and ______ the existing flux lines ______ |
The Center of the wire, push, outwards |
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