Electromagnetism, Magnetism Flashcards

Terms Definitions
Ammeter
Current-measuring device.
To push away.
Repel
an aurora
the Northern Lights
generating electricity with motion
mechanically
a push or pull
force
Insulators have _______ resistance.
High
Pull toward each other.
Attract
properties and interactions of magnets
magnetism
like magnetic poles
repel each other
unlike magnetic poles
attract each other
what opposite magnetic poles do
attract
The ends of a magnet.
Poles
Define magnetic field.
Zone of influence.
magnet
Something that can attract magnetic materials.
common ferromagnetic materials
iron, nickel, and cobalt
composed of chemical substances which can generate electrical current
battery
A magnet's property of attracting certain materials, mainly iron and steel
magnetism
south pole
One end of a magnet.
attract
Two things pulling towards each other.
index finger
magnetic lines of force field
an electric current produces
a magnetic field
a spinning electron
produces a magnetic field
Give examples of diamagnetic materials.
Water, Bismuth
Generator
Device that converts mechanical energy to electrical energy.
nickel
A metal that is a magnetic material.
solenoid
a coil of wire with a current
The flow electrons is known as _____
electricity
electromagnet
A coil of wire with electricity flowing in it. An electromagnet has a magnetic field like a bar magnet.
can attract or repel each other
two magnets
a machine that converts motion into electricity using magnets
generator
Define motor.
Device that is supplied with electrical current to produce mechanical motion.
Give examples of nonmagnetic materials.
Glass, plastic, wood
What type of current does a galvanometer use?
DC
Define magnetism.
Ability of certain materials to attract iron, cobalt, nickel.
If you want to produce a large, continuous amount of electricity you need a _____.
Generator
the two ends of a solenoid
act like poles
Electromagnets
is a temporary magnet produced by a moving electric current
A south pole and a north pole will...
attract
an object that has the property of attracting certain materials, mainly iron and steel
magnet
The production of electricity by means of a coil of wire moving in a magnetic field is called . . .
electromagnetic induction
A south pole and a south pole will...
repel
compass
A magnetised piece of metal that can swing around – it points north.
The flow of electrons is known as what?
Current
Soft iron has __ permeability, __ retentivity.
High, low
Hard iron has __ permeability, __ retentivity.
Low, high
Define magnetic retentivity.
Ability of magnet to resist demagnetization.
Maximum induction will occur when a conductor cuts a magnetic field at what angle?
90 degrees
A strong electromagnet needs to have a core made of . . .
soft iron
iron filings
Tiny pieces of iron that are sometimes used to find the shape of a magnetic field.
the space around a magnet within which the force of the magnet can act
magnetic field
A turbine is connected to a generator to produce electricity. The turbine can be turned using steam. The steam can be created by burning ___________.
fossil fuels
steel
A mixture made mainly from iron; it is a magnetic material.
Electricity running through wires produces a ________.
magnetic field around the wire.
charge that collects on the surface of an object
static electricity
magnetic field
the region around a magnet where the magnetic force is exerted
armature
The iron part of a relay that moves when electricity is flowing in the solenoid (or electromagnet).
Define electromagnetism.
The branch of physics that deals with the relationship between electricity and magnetism.
What is a stator?
Consists of pairs of stationary magnets arranged around the rotor.
T/F: A magnetic field exists around a wire only while an electric current is flowing.
True
Define self-induction.
Induction of an opposing emf in a single coil by its own changing magnetic field.
since Earth produces a strong magnetic field,
Earth can make magnets
Explain how Magnetic force decreases
the magnetic force of attraction between two magnets decreases with distance
north pole
One end of a magnet. This ends points north if the magnet can move.
north magnetic pole
The place on the Earth where compasses point (it is not in the same place as the North Pole marked on maps).
reed switch
A switch made from two thin pieces of metal, which closes when it is in a magnetic field.
Describe the induction motor.
Has stator with even number of electromagnets. Has rotor in middle.
What are the 3 classes of magnets?
Natural, Artificial Permanent, Electromagnet
What are the 4 magnetic classes of matter?
Diamagnetic, Ferromagnetic, Nonmagnetic, Paramagnetic
What is an electric motor?
Device that converts electrical energy into mechanical energy.
Differences beween electron flow & conventional current flow
electron flow is actually from negative to positive poles while conventional electric current is described as going from positive to negative poles.
A magnet can be de-magnetised by placing it inside a coil carrying . . .
alternating current Because This scrambles the atomic magnets and reduces the magnetic field in the magnet to zero
What will happen if the negative pole of one magnet is brought near the negative pole of another magnet?
the magnets will repel
One of the ends of a magnet where the magnetic force is strongest; it points to the north when the magnet moves freely.
north pole
List characteristic of diamagnetic matter.
Weakly repelled from both poles of magnetic field.
Name one of four factors that determine electromagnetic induction.
STRENGTH between conductor and direction of magnetic field.
List characteristic of paramagnetic matter.
Weakly attracted to both poles of magnetic field.
When an alternating voltage is applied across the primary coil of a transformer . . .
an alternating voltage is produced (induced) across the secondary coil
What are the two poles of an electromagnet?
positive (+) and negative (-)
you can increase the strength of an electromagnet's field by
using a stronger ferromagnetic material for the core; increasing the current in the solenoid; increasing the number of loops in the solenoid; and winding the coils more tightly
Electricity supplied by the National Grid is at 400 000 volts. This is too high to use in the home so the voltage must be . . .
reduced by a transformer, called a 'step-down' transformer
What metal is attracted to magnets?
Iron (also cobalt and nickel) NOT "METAL"- MOST METALS ARE NOT MAGNETIC
What did OERSTED discover in 1820?
That a magnetic field always surrounds a conductor in which a current is flowing.
4 factors controlling strength of electromagnetically induced current
1- the strength of the magnetic field; 2- the speed of the motion b/t lines of force & conductor; 3- the angle b/t the magnetic lines of force & the conductor; 4- the number of turns in the conduction coil
Reversing the current direction in an electromagnet . . .
reverses the poles Because This is what AC does 50 times a second
What are the 3 Laws of Magnetism?
Every magnet has 2 poles; like repells-opposite attracts; the inverse square law
when molten material hardens into the rock on the ocean floor,
the domains of the iron it contains line up in the direction of Earth's magnetic field
An electromagnet needs to have ________.
wire wrapped around an iron core and a battery or other electrical energy source
A transformer needs a soft iron core because . . .
it transfers the magnetic field from the primary to the seconday coil. Only AC can produce a rapidly changing magnetic field
The current is taken from a generator by means of . . .
slip rings and brushes. This prevents sparks ( or tangled wires ).
Describe what happens when you touch a piece of iron to a permanent magnet
magnetism is induced in the piece of iron, and it becomes a temporary magnet. Magnetism can be induced only in iron or steel, cobalt and nickeland a few other metals.
To increase the voltage induced in a coil rotating in a magnetic field we could . . .
increase its area or the number of turns Or make the field stronger
A magnet exerts a force on any piece of material which is . . .
magnetic Because Means affected by a magnet !
If light bulbs are connected on a series circuit removing one bulbs will cause ______
all the other bulbs on the circuit to go out
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