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Level 175

Magnetic, Electric & Gravitational Fields


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What are the origins of magnets?
Stone from Magnesia, a part of ancient Greece where lodestones were found.
What is magnetism?
A non-contact force of attraction or repulsion that acts at a distance
Magnet ends.
What are poles?
What makes a magnet a magnet?
How the atoms' in the magnetic field is arranged.
What are magnetic domains?
Region where the magnetic fields of atoms are aligned.
What are electromagnets?
A type of magnet whose magnetic field is produced by the flow of electric current.
How do electromagnets work?
By running an electric current through a wire, you can create a magnetic field. Electrons will flow from the negative side to the positive side of a battery as fast as possible. A small magn…
How can you make and electromagnet?
Wrap an insulated wire around an iron core. If you attach a battery to a wire, an electric current will begin to flow and the iron core will become magnetized.
In what direction does a bar magnet align itself?
Aligns with magnetic north-south of the Earths magnetic field.
What's a magnetic field line?
A line drawn in a magnetic field so that the tangent to it at any point shows the direction of the magnetic field at that point is called a magnetic field line.
What's a solenoid?
A solenoid is a coil whose length is much larger than its radius. When a current is passed through the solenoid it creates a magnetic field.
How can a solenoid's magnetic field be increased?
When a soft iron core is placed at the centre of a solenoid it acts as like a magnet, normally known as an electromagnet.
Give a use for an electromagnet.
Uses of such magnets can be found in most electric motors.
What is a permanent magnet?
A magnet that retains its magnetism after being removed from a magnetic field.
What is a temporary magnet?
An object that loses its magnetism after short time.
What is a ferromagnet?
Strong magnetic properties, such as iron, become a ferromagnet when the magnetic domains are aligned well.
What are electric field lines?
Lines that provide a picture of an electric field, indicate the field's strength by the spacing between the lines, never cross, and are directed toward negative charges and away from positive charges.
Magnetic poles cannot exist alone; however, electric charges can.
What is the difference between magnetic poles and electric charges?
What is an electric field?
The field around charged particles that exerts a force on other charged particles.
What is a field?
A push or a pull on an object using lines to represent the force.
What is mass?
Amount of matter in an object.
What is weight?
The force of gravity on an object
What is a gravitational field?
A force field that exists in the space around every mass or group of masses
What is gravity?
A force of attraction between objects that is due to their masses and distance.
the WEAKER the gravitational pull
The MORE distance between two objects..
The LESS mass an object has...
the LESS gravitational pull it will have
The MORE mass an object has...
the MORE gravitational pull it will have
the STRONGER the gravitational pull
The LESS distance between two objects...
What are motors?
A device that converts electrical energy to mechanical energy.
What are generators?
A device that converts mechanical energy into electrical energy.
The Law of Magnetic Poles
Like poles repel, opposites attract
vector
a displacement distinguished by magnitude and direction but not by location.
field lines
run from the N pole of the magnet to the S pole
direction
A point toward something, determined by its orientation and sense.
Closed loops
Magnetic field lines always form closed loops. They never cross.
Spacing
The gap between field lines represents the strength of the magnetic field.
Dot
Represents a vector coming towards you/out of the page
Cross
Represents a vector going away from you/into the page.
Movement of charge
Produces a circular magnetic field around the conductor.
Right-hand grip rule (conductor)
Shows the direction of the relationship between a current and the generated magnetic field.
Coils
Magnify the magnetic field around the coil.
Solenoid
A coil of insulated wire, usually wrapped around an iron core.
Right-hand grip rule (solenoid)
Fingers show the direction of current around the coil, thumb shows the magnetic field direction.
electromagnet
a large number of closely spaced turns of wire that create the magnetic field when hooked up to a battery
Strong electromagnet
Lots of current, lots of turns, lots of soft iron.
magnet
a body that can attract certain substances, such as iron or steel, as a result of a magnetic field
magnetic field
a vector force field that surrounds any magnetic material
magnitude of a magnetic field
a measure of the strength of a magnetic field
direction of a magnetic field
The direction of a magnetic field at a given location is defined as the direction a compass needle would point if placed at that location.
magnetic pole
either of two regions of a magnet, designated north and south, where the magnetic field is strongest
north pole
the end of a freely rotating bar magnet that points toward the north geographic pole of Earth
south pole
the end of a freely rotating bar magnet that points toward the south geographic pole of Earth
magnetic domain
a region within a magnetic material where the electrons are aligned in the same direction
magnetized
temporarily or permanently magnetic from exposure to a magnetic field
non-magnetized
not magnetic
Permanent Magnet
a magnet that retains its magnetism after being removed from a magnetic field
temporary magnet
a piece of magnetic material that does not retain its magnetism after the magnetic field producing it has been removed
core
a piece of magnetic material, such as soft iron, placed inside the windings of an electromagnet or transformer to intensify and direct the magnetic field
magnetic compass
a compass having a magnetized needle generally in line with the magnetic poles of the earth
magnetic force
a the force of a magnet