magnetism Flashcards
study of stationary charges
electrostatics
electric fields radiation ______ a positive charge
out from
electric fields radiation ______ a negative charge
towards
a region around a charged particle within which it can exert a force or have a force exerted upon it by other charged particles
electric field
Particles with opposite charged electric fields attract each other as positive charges will have electrical field lines ___________, and negatively charged particles will have electrical field lines ______________
going out of it, coming towards it
magnetism (is/is not) a fundamental property of some forms of matter
is
the ability of certain materials to attract iron, cobalt, or nickel
magnetism
magnetism: the ability of certain materials to attract __________________
iron, cobalt, or nickel
Magnetism is the ____________________________ due to the arrangement of its atoms, particularly its electrons.
force of attraction or repulsion of a magnetic material
3 laws of magnetism
1. Every magnet, even if it is one charged particle like an electron or proton in motion, has a ___________
2. Like poles _____ each other and unlike poles _____ each other
3. The attractive or repulsive forces varies directly as a function of the ____________ and _________________ between them (Inverse Square)
- North and South Pole
- like, attract
- strength of the poles, the square of the distance
most all magnets are _________
dipoles
In magnetic materials, orbiting electron spin in one direction.
dipole
when a number of these dipoles (atomic magnets) align with each other, they create a grouping called a ___________
magnetic domain
magnetic domains aligned = _____________
magnet
Orbital electrons of atoms spin in predominately ___ direction; this creates ___________
one; dipoles
magnetic fields have 3 general principles
1. lines of force travel from _______ to the ________
2. Lines of force in the ____ direction repel each other while lines of force in ________ directions attract each other
3. magnetic fields are distorted by ________ and unaffected by _______
- north, south
- same; difference
- magnetic materials; nonmagnetic materials
Magnetic fields consist of lines of force in space called _____
flux
Unit of measurement for magnetic field strength
Tesla (T)
a measurement of the total magnetic field which passes through a given area. It’s created when magnetic dipoles orient in one direction to create a magnet
magnetic flux
when an electron moves in orbit around the nucleus, it creates a magnetic field __________ to its motion.
perpendicular
A magnetic field is a (closed/open) loop moving with the charged particle
closed
3 types of magnets
Natural Magnets, Artificial Permanent Magnets, Electromagnets
natural magnet characteristics
1. also called _________
2. essentially, a large piece of ______, which is ____. Thought to have gained magnetism from the ___________
3. They are permanent magnets in that they will remain magnetic unless something happens to change the alignment of their electrons
- lodestones
- magnetite, iron ore, Earth’s magnetic field
artificial permanent magnet characteristics
1. ________; alignment of atoms is induced using _________
2. Non magnetized magnetic material is exposed to a strong magnetic field which pushes and pulls the atoms into alignment using the forces of repulsion and attraction
3. (Most/not many) magnets have been artificially created
- manufactured; magnetic induction
- most
electromagnets characteristics
1. In its simplest form, it is an ____ bar wrapped with a ____ carrying an electric current
2. This creates a magnetic field due to the ____________
3. It is only magnetic while the current is ________
4. Many applications in ___________
- iron, wire
- flow of electricity
- running
- electrical equipment
nonmagnetic materials: are not affected by magnetic fields (example: _______________)
(wood, glass, plastics, etc.)
diamagnetic materials: weakly repelled by magnetic fields (________________)
water, mercury, gold, etc.
paramagnetic materials: those weakly attracted to magnetic fields (____________________)
plutonium, gadolinium, aluminum, etc.
ferromagnetic material: materials that are strongly attracted to magnetic fields (________________)
iron, cobalt, nickel, etc.
how to induce magnetism in a ferromagnetic material
place material in magnetic field, rubbing material against a permanent magnet
how do you demagnetize a magnet?
Heat it to a very high temperature, dropping it or hammering it repeatedly, bringing the magnet in contact with the like poles of other magnets repeatedly
How long do permanent magnets keep their magnetism?
A magnet should not lose more than 1% of its strength over 100 years
if you cut a magnet, will each piece still have a north or south pole?
yes
a variable resistor used to control current
rheostat
Oerstead’s principles
1. Electric current creates a ________________
2. Because it had such an affect on the compass, the created magnetic field was _________________
- magnetic field
- stronger than the Earth’s
if you were to put a _____ wire carrying a current (the conductor), the magnetic field from the wire is (weakened/strengthened) as the flux lines inside the loop are _______________________
loop, strengthed, concentrated and overlapping
The configuration of coiled wire increasing in strength
solenoid
modified right hand rule: If you grab the solenoid with your right hand so that the fingers are wrapped around it in the direction of the___________________ the thumb will be pointing the direction of the ______________ pole of your electromagnet
current flow (not electron flow), magnetic north
galvanometer measures __________ and __________ of electric current
magnitude and direction
An electric current is induced in a circuit if some part of that circuit is exposed to a __________________. This produces _____________
changing magnetic field; alternating current (AC)
Doubling the strength of the magnet will ___________________________
double the induced voltage
Moving the magnet through the coils twice as fast, or moving the coils over the magnet twice as fast will ____________________-
double the induced voltage
the generation of an induced alternating current in a secondary coil by supplying an alternating current to a primary coil
mutual induction
an induced current is always ___________
alternating current
the generation of an induced current that opposes any change in current existing in the circuit whether it an increase or decrease.
self induction
self induction occurs when the alternating current within the induced circuit creates _________________
its own magnetic field that induces a second current to flow within the wire, but in the opposite direction.
with mutual induction, it is not necessary to physically move a magnet near a coil to induce an electric current. All that is needed is for there to be a change in the _______________ of the inducing magnetic field.
intensity or strength
changing intensity or strength of the magnetic field for induction can be done by placing __________________________ near the secondary coil
an electromagnet that has alternating current (AC) running through it
Lenz’s law states an induced current flows in the ____________ direction of the magnetic field change that produced it
opposite
electric field lines are ________; magnetic field lines are ___________
monopoles (linear); dipoles (closed loop)
magnetic field lines are also called ____________
flux lines
right hand rule: thumb is _________; fingers are ____________
direction of electric current; direction of magnetic flux (field lines)
Faraday’s law four basic factors
The magnitude of the induced current depends upon:
1. The strength of the magnetic field
2. The velocity of the magnetic field as it moves past the conductor (wire)
3. The angle of the conductor to the magnetic field
4. The number of turns in the conductor (coils)
Self inductance always ____________
opposes the changing current
