quiz Flashcards
, it has the ability to exert forces on magnets or other magnetic materials.
magnetic
is a material that keeps its magnetic properties even when it is NOT close to other magnets.
permanent magnet
two opposite poles of magnet
north and south pole
Magnets exert forces of each other
The forces depend on the alignment of the poles
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Plastics, wood, and most insulating materials are virtually transparent to magnetic forces.
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Conducting metals, like aluminum, also allow magnetic forces to pass through, but may change the forces.
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The strength of the force between magnets depends on the distance between them.
The magnetic force decreases with distance much faster than does either gravity or the electric force.
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All magnets create a magnetic field in the space around them, and the magnetic field creates forces on other magnets.
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The number of field lines in a certain area indicates the relative strength of the magnetic field in that area.
The arrows on the field lines indicate the direction of the force.
The closer the lines are together, the stronger the field.
Magnetic field lines always point away from a magnet’s north pole and toward its south pole
magnetic field
The sources of nearly all magnetic effects in matter are the electrons in atoms.
There are two ways in which electrons create magnetism:
Electrons around the nucleus and their motion makes the entire atom a small magnet.
Electrons themselves act as though they were magnets.
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All atoms have electrons, so you might think that all materials should be magnetic, but there is great variability in the magnetic properties of materials.
The electrons in some atoms align to cancel out one another’s magnetic influence.
While all materials show some kind of magnetic effect, the magnetism in most materials is too weak to detect without highly sensitive instruments.
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, the electrons are oriented so their individual magnetic fields cancel each other out.
diamagnetic materials
Individual atoms in _______ materials are magnetic but the atoms themselves are randomly arranged so the overall magnetism of a sample is zero.
paramagnetic
A small group of metals have very strong magnetic properties, including iron, nickel, and cobalt.
These metals are the best known examples of _______ materials.
ferromagmetic
Magnetic Properties of Materials
A small group of metals have very strong magnetic properties, including iron, nickel, and cobalt.
These metals are the best known examples of ferromagnetic materials.
Atoms with similar magnetic orientations line up with neighboring atoms in groups called _____________
magnetic domains
Magnetic Properties of Materials
Magnetic domains in a ferromagnetic material will always orient themselves to attract a permanent magnet.
If a north pole approaches, domains grow that have south poles facing out.
If a south pole approaches, domains grow that have north poles facing out.
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Materials that make good permanent magnets are called _____ magnets
hard
Steel, which contains iron and carbon, is a common and inexpensive material used to create hard magnets.
Materials that lose their magnetism quickly are called ____magnets
soft
The Earth’s Magnetic Field
As early as 500 B.C. people discovered that some naturally occurring materials— such as lodestone and magnetite—have magnetic properties.
By 1200, explorers from Italy were using a compass to guide ocean voyages beyond the sight of land.
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The Earth’s Magnetic Field
When you use a compass, the north-pointing end of the needle points toward a spot near (but not exactly at) the Earth’s geographic north pole.
The Earth’s magnetic poles are defined by the planet’s magnetic field.
That means the south magnetic pole of the planet is near the north geographic pole.
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what is a magnet
What is a magnet?
A magnet will pull some metals towards itself.
Metals that contain iron, nickel, and cobalt are magnetic. In other words, a magnet will pull them.
ability of a magnet to attract another object.
magnetism
The region where the magnetic forces
act is called
magnetic field
Every magnet has at least one north pole and one south pole. (magnetic field lines leave the North end of a magnet and enter the South end of a magnet)
If you take a bar magnet and break it into two pieces, each piece will again have a North pole and a South pole.
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A temporary magnet made by passing electric current through a wire coiled around an iron bar.
electromagnet
consists of an iron core placed inside a wire coil. The magnetic field strength of a wire coil carrying an electric current increases in direct proportion to the number of turns of the coil.
electromagnet
discovered the deflection of a compass needle while performing a demonstration for his students
discovered the fundamental connection between electricity and magnetism
Hans Christian Oersted
A current-carrying wire becomes a magnet by setting up a magnetic field around it.
Our proof for this is the deflection of the compass needle.
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According to Oersted’s experiment…
A current-carrying wire produces a magnetic field .
successfully connected electricity and magnetism
aligned a straight wire with a compass pointing to Earth’s magnetic north
when current is present, the needle deflects perpendicular to the wire
when the current is reversed, the needle deflects in the opposite direction
Oersted’s principle
“a charge moving through a straight conductor produces a circular magnetic field around the conductor”
Remember: electric current from + to the – terminal of the battery
Right hand grip rule
Current is coming out of the paper.
Counter-clockwise!
If the current through the wire increases, the strength of the induced magnetic field increases.
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a long coil of several turns of wire
solenoid
The magnetic field inside a solenoid is stronger than the magnetic field outside it.
The concept of solenoid led to the creation of a simple electromagnet.
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If the number of coils in a wire increases, the strength of the induced magnetic field increases.
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invented electric motor, generator and transformers
discovered electromagnetic induction
discovered laws of electrolysis
Michael Faraday
Faraday’s conclusion
An electrical current is produced by a changing magnetic field
The discovery of Faraday paved the way to the development of the generator, transformer and other devices that made the production of electricity cheaper.
It converts mechanical energy to electrical energy.
generator
flows in one direction.
direct current
current that flows in a back-and-forth manner
alternating current
A device that transforms electrical energy to mechanical energy.
motor
A device that transforms mechanical energy to electrical energy.
generator
