Flashcards
Introduction to Magnetism (Mod.4 Sect.1 Part 1)
Flashcards do conjunto (45)
- 1In general terms, a _____ is a special bar of iron that can attract and hold other pieces of iron to it.magnet
- 2_______ - The power of attraction between a magnet and iron; It's caused by the motion of electric charges; It's the force exerted by magnets when they attract or repel each otherMagnetism
- 3The term _____ is used to refer to both natural and artificial magnets.magnet
- 4______ magnets are ores that have the unusual ability to attract pieces of iron placed close to them.Natural
- 5Natural magnets are sometimes called ______.lodestones
- 6An ______ magnet is simply a man-made magnet that has all the properties of a natural magnet.artificial
- 7Straight artificial magnets are called ____ magnets.bar
- 8Curved artificial magnets are called _____ magnets.horseshoe
- 9Artificial magnets that keep their properties for long periods of time are called _____ magnets.permanent
- 10Very strong artificial magnets can be made by compressing magnetic powder under high pressure and temperature. These magnets are called _______ magnets and are used in devices such as DC motors and high-power loudspeakers.rare earth
- 11When a magnetic metal core is wrapped in a coil of wire and electric current is applied to the wire, a magnetic field forms around the core. This device is called an _________ and is used to create mechanical motion. (ex. relays & motors)electromagnet
- 12The ends of a magnet are called the _____.poles
- 13There are two opposite poles on a magnet: the _____ pole and the _____ pole.north, south
- 14The strongest force of magnetic attraction is located at the _____ of a magnet.poles
- 15The ____ is the imaginary line that's drawn through the center of a magnet.axis
- 16The _______ is the point that falls exactly halfway between the poles of a magnet. Little magnetic force is present at this spot.neutral line
- 17A piece of soft iron called a _____ joins the two ends of a horseshoe magnet. This piece helps the magnet retain its magnetism for long periods of time when it's not in use.keeper
- 18In an _______, the location of the poles depends on the direction of current flow in the wire coil.electromagnet
- 19Magnets and electromagnets always attract _____ metals.ferrous
- 20Ferrous metals are metals that contain _____.iron
- 21Copper, brass, aluminum, and some types of stainless steel are unaffected by magnets. These materials are often referred to as _______.nonferrous
- 22The forces of magnetic attraction and repulsion flow in definite directions or "lines" around a magnet. These lines of magnetic force are called ________.magnetic flux
- 23The area of space around a magnet in which the lines of force move is called a _________.magnetic field
- 24The lines of force move in a specific path around a magnet. This path is called the magnetic _____. Each line of force leaves the from north pole, makes a complete path around the magnet, then returns in the south pole. From there it goes through the magnet to the N. pole again.circuit
- 25Materials that have very little opposition to lines of force are called _____ or __________ materials.magnetic, ferromagnetic
- 26Materials that have a strong opposition to lines of force are called ________ materials.nonmagnetic
- 27The process by which an object is magnetized by the magnetic field of a magnet is called ____________.magnetic induction
- 28Three types of magnetic circuits are: ____, ______, and _____.simple, compound, closed
- 29A _____ magnetic circuit is a circuit in which all the lines of force are contained within the magnetic material.simple
- 30A _____ magnetic circuit is a circuit that consists of two or more magnetic materialscompound
- 31A _____ magnetic circuit is composed entirely of magnetic material. The lines of force don't pass through an air gap or any other nonmagnetic material.closed
- 32Magnetic ____ is a measurement of the total magnetic field which passes through a given area.flux
- 33The standard unit of magnetic flux is the ______. One of these units is equal to one line of force.maxwell
- 34A large unit of magnetic flux is the ______. One of these units is equal to 100-million maxwells, or 100-million lines of force.weber
- 35_________ is the number of lines of force in a given unit area.Flux density
- 36Flux density is expressed in a unit called ____. One of these units is equal to one maxwell per square cm.gauss
- 37A large unit of flux density is a ____ which is equal to one weber per square meter.tesla
- 38____________ is what pushes magnetic flux through a magnet. (voltage for magnets :D)Magnetomotive force
- 39The abbreviation for magnetomotive force is ____.MMF
- 40In a magnetic circuit, the materials opposition to magnetic flux is called ______.reluctance
- 41The MMF that pushes flux through an electromagnet is measured in _______.ampere turns
- 42The MMF exerted per unit of length of magnetic material is called the magnetic ________.field intensity
- 43Magnetic field intensity is represented by the letter H and is measured in units called ____________.ampere tuens per meter
- 44In any magnetic material, the relationship between the magnetic field intensity and the flux density can be illustrated by the ___________.magnetization curve
- 45A __________ is needed to demagnetize a magnetic material.coercive force
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