Magnetism Flashcards
Magnetic inclination is the least at the.
equator.
Ferromagnetic materials can be magnetized.
below a certain temperature.
Glass is an example of a.
diamagnetic material.
A solenoid of 10 turns per metre carries a current of 5A. If the current is reduced to 2.5A, how many turns would be required to maintain the same magnetic field?
20.
Which of the following materials is easiest to magnetize?
Soft iron.
To find which end of an electromagnet is the north pole, use the.
Right Hand Clasp Rule.
The earth’s magnetic field is greatest at the.
magnetic poles.
The lines of magnetic flux from a magnet will.
repel each other.
Of the following which pair of materials would most readily become magnetized?
Iron and steel.
The core material used for an electromagnet is soft iron because.
it demagnetizes easily.
If the North pole of a magnet is brought nearer to the North pole of another magnet.
repulsion between them will be increased.
Where is the magnetic dip least?
Equator.
When a number of ferrite pieces are grouped together, they.
can be used to store binary code.
Ampere turns is calculated by the number of turns.
multiplied by current.
The unit of flux is the.
Weber.
Lines of magnetic flux pass from.
North to South.
Why is ferrite used in memory circuits?
High remanence.
Magnetic lines are flowing parallel. They will.
repel each other.
The horizontal component of the earth’s magnetic field is most strongly felt at.
equator.
Two parallel lines of magnetic flux in the same polarity.
repel each other.
Magnetic fields around two parallel conductors carrying current in the same directions will.
attract.
Magnetic field on a solenoid is.
weakest outside the coil.
Which of the following is absolute permeability?
µ(micro).
The symbol for flux density is.
B(capital).
A paramagnetic material has a relative permeability of.
greater than unity.
Through which material will magnetic lines of force pass the most readily?
Iron.
Permanent magnets have.
high reluctance, high coercive force.
The term used to denote the strength of a magnetic field is.
flux density.
A soft iron core is used in an ELECTRO magnet because.
it has HIGH permeability and LOW coercivity.
A non-magnetic metal.
has no permeability.
What is the effect of inserting an iron core into a current carrying coil?
The flux density of the original magnetic field produced by the coil is increased.
Flux density will.
increase linearly with magnetic flux.
Storage of magnets should be.
in pairs with keeper plates.
The hysteresis loop for a magnetic material is on a graph with.
flux density against magnetising force.
A material with a narrow hysteresis loop.
will have low retentivity.
If a bar magnet is cut in half.
two bar magnets are formed.
Copper is a.
diamagnetic material.
The MMF of a coil fed with 2 amps and having 10 turns is.
20 ampere turns.
An example of a paramagnetic material is.
iron.
Vibration in a magnet causes.
flux to decrease.
Permeability of a material can be found by.
flux density / MMF.
When magnetizing a piece of material, magnetic strength will rise.
non-linearly with magnetic force.
A material exposed to heat will.
be harder to magnetise.
If cobalt has a permeability of 4800 it is a.
ferromagnetic.
A material exposed to heat will
be harder to magnetise.
The ‘curie’ temperature is the temperature above which the material cannot be magnetised.
If cobalt has a permeability of 4800 it is a
ferromagnetic.
Cobalt is a hard ferromagnetic silver-white element. http://en.wikipedia.org/wiki/Cobalt
Cobalt has a permeability
greater than unity.
NIL. http://en.wikipedia.org/wiki/Cobalt
Magnetic flux
exist in all space around the magnet.
NIL.
The ability of a circuit to produce a magnetic flux under the influence of a MMF
permeability.
Aircraft Electrical System. Pallett 3rd Edition appendix one page 196.
Magnetic flux saturation takes place when
the magnetised medium will accept no further lines of flux.
See a B-H diagram.
Cables are shielded to prevent ‘H’ magnetic interference in wires with the following material
Copper braiding.
Aircraft Electricity and Electronics, Eismin 5th edition Page 78.
Spontaneous magnetism is associated with
ferromagnetic materials.
NIL. http://www.geo.umn.edu/orgs/irm/hg2m/hg2m_b/hg2m_b.html.
