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8J Magnetism @ AJHS
magnets and electromagnets
|Two things pulling towards each other.
|A metal that is a magnetic material.
|A metal that is a magnetic material.
|Something that can attract magnetic materials.
|Materials that are attracted to a magnet; iron cobalt nickel and steel are all magnetic materials.
|A non-contact force.
|A metal that is a magnetic material.
|One end of a magnet. This ends points north if the magnet can move.
|One end of a magnet.
|A mixture made mainly from iron; it is a magnetic material.
|A straight magnet, shaped like a small bar.
|A magnetised piece of metal that can swing around – it points north.
|The end of a magnet that points north if the magnet can move freely. Often just called the north pole.
|The end of a magnet that points south if the magnet can move freely. Often just called the south pole.
|Tiny pieces of iron that are sometimes used to find the shape of a magnetic field.
|The space around a magnet where it can affect magnetic materials or other magnets.
|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).
|A small compass used for finding the direction of a magnetic field.
|The iron part of a relay that moves when electricity is flowing in the solenoid (or electromagnet).
|A coil of wire with electricity flowing in it. An electromagnet has a magnetic field like a bar magnet.
|make and break
|The switch in an electric bell that opens and closes. It is operated by a switch; electromagnet that breaks the circuit whenever it is switched on.
|A magnet that keeps its magnetism – it does not depend on electricity.
|A switch made from two thin pieces of metal, which closes when it is in a magnetic field.
|A switch that is switched on and off by electricity.
|A coil of wire.
|A solid bar inside an electromagnet – usually made of iron.
|properties and interactions of magnets
|The collection or flow of electrons in the form of an electric charge
|generating electricity with motion
|surrounds an electric charge and exerts a push or pull on other electric charges
|charge that collects on the surface of an object
|charge that flows through a conductor
|composed of chemical substances which can generate electrical current
|electric current running through a wire coiled around a metal core produces this
|the way most of our electricity is produced
|a machine that converts motion into electricity using magnets
|what opposite magnetic poles do
|To strengthen an electromagnet you should (decrease / increase) the number of loops of wire around the nail.
|In a (parallel / series) circuit electricity can only travel ONE path.
|The flow electrons is known as _____
|Conductors have _____ resistance.
|Adding bulbs on a series circuit will cause all of the lights (to get dimmer / to stay the same brightness)
|to get dimmer
|If a material is used to close a circuit and the light does not light it is probably because the material used to close the circuit is a(n) ______ (conductor / insulator)
|If you want to produce a large, continuous amount of electricity you need a _____.
|If light bulbs are connected on a series circuit removing one bulbs will cause ______
|all the other bulbs on the circuit to go out
|An electric motor changes _____ energy into ______ energy.
|electric energy into mechanical energy.
|Wood would be classified as a _______ (conductor / insulator)
|A turbine is connected to a generator to produce electricity. The turbine can be turned using ______, ______, or _______.
|wind, flowing water, steam
|A discharge of static electricity in nature is known as ________
|In a parallel circuit light bulbs can be connected in (a straight line / loops made of wires).
|loops made of wires
|Insulators have _______ resistance.
|In a (parallel / series) circuit electricity can travel MORE THAN ONE path.
|Adding bulbs on a parallel circuit will cause all of the lights (to get dimmer / to stay the same brightness)
|to the same brightness
|Plastic would be classified as a _______ (conductor / insulator)
|Copper would be classified as a _______ (conductor / insulator)
|Electricity running through wires produces a ________.
|magnetic field around the wire.
|In a series circuit light bulbs can be connected in (a straight line / loops made of wires).
|a straight line
|Fabric would be classified as a _______ (conductor / insulator)
|Objects become electrically charged when they gain or lose _______
|If you plug a small 1.5V light into a 120V outlet the light will ________.
|overheat from too much current
|Magnetic fields are caused by moving ________.
|ALL of the lights connected on a series circuit will (brighter / dimmer) than lights connected on a parallel circuit.
|An electromagnet needs to have ________.
|wire wrapped around an iron core and a battery or other electrical energy source
|A turbine is connected to a generator to produce electricity. The turbine can be turned using steam. The steam can be created by burning ___________.
|A generator changes _____ energy into ______ energy.
|mechanical energy into electrical energy.
|Electrons usually flow from _____ to ______
|negative to positive.
|A stone or piece of metal that can attract certain things.
|Pull toward each other.
|The force or energy that magnets possess.
|A rock found in the Earth.
|To push away.
|The ends of a magnet.
|An object made with a magnet that can help you find your way.
|The area around a magnet in which the force of the magnet acts.
|A south pole and a south pole will...
|A south pole and a north pole will...
|an object that has the property of attracting certain materials, mainly iron and steel
|A magnet's property of attracting certain materials, mainly iron and steel
|One of the ends of a magnet where the magnetic force is strongest; it points to the north when the magnet moves freely.
|One of the ends of a magnet where the magnetic force is strongest: it points to the south when the magnet is allowed to move freely
|The lines that form a pattern showing the size and shape of a magnetic force field.
|lines of force
|the space around a magnet within which the force of the magnet can act
|A naturally magnetic mineral found at or near Earth's surface.
|A device containing a magnetized needle that moves freely and is used to show direction.
|a push or pull
|an object that sticks to iron
|a specific kind of force
|when magnets pull together
|when magnets pull apart
|a piece of iron that behaves like a magnet when it is touching a permanent magnet
|the influence of a permanent magnet's magnetic field on a piece of iron, which makes the magnet act like a magnet
|What is the affect of distance between two magnets
|greater the distance the weaker the force of attraction
|can attract or repel each other
|what detects a magnetic field?
|compasses, iron fillings, and iron, cobalt or nickel objects
|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.
|Explain how you stop force of magnetism
|Thick objects and sheets of steel stop magnetism
|Explain how Magnetic force decreases
|the magnetic force of attraction between two magnets decreases with distance
|Explain how you detect a magnetic field
|compasses, iron fillings, and iron objects
|stop the force of magnetism
|thick objects and sheets of steel
|What metal is attracted to magnets?
|Iron (also cobalt and nickel) NOT "METAL"- MOST METALS ARE NOT MAGNETIC
|What are the two poles of a permanent magnet?
|positive (+) and negative (-)
|What are the two poles of an electromagnet?
|positive (+) and negative (-)
|What happens when two like magnetic poles are brought together?
|the magnets will repel
|What happens when two opposite magnetic poles are brought together?
|the magnets will attract
|What else will effect a magnet besides iron,( cobalt, and nickel)?
|What important difference is there between permanent magnets and electromagnets?
|electromagnets can be turned on and off and permanent magnets cannot
|How is an electromagnet created?
|by passing electricity through a coil of wire
|How is electricity generated?
|by passing a magnet through a coil of wire
|What force powers an electric motor?
|What force powers an engine?
|What causes a motor to spin?
|the poles of the stationary magnets repel the poles of the moving magnet (armature)
|What are the four principal ways of generating electricity?
|wind, moving water, burning fossil fuels, and nuclear
|What will happen if the positive pole of one magnet is brought near the positive pole of another magnet?
|the magnets will repel
|What will happen if the negative pole of one magnet is brought near the positive pole of another magnet?
|the magnets will attract
|What will happen if the negative pole of one magnet is brought near the negative pole of another magnet?
|the magnets will repel
|A magnet exerts a force on any piece of material which is . . .
|magnetic Because Means affected by a magnet !
|Magnetic materials include . . .
|iron, steel, nickel and
|The region of space around a magnetic which can influence magnetic materials is called a . . .
|The magnetic field of a magnet can be made visible by using . . .
|iron filings or plotting compasses
|The end of a bar magnet which turns to point North is called the . . .
|A bar magnet which is suspended by a thread will eventually . . .
|come to rest pointing North-South Because The magnet aligns itself with the Earth's magnetic field
|The Earth has a magnetic field around it which resembles that of a . . .
|bar magnet Because It looks similar but this does not mean there is a bar magnet at the centre of the Earth
|When a coil of wire has an electric current flowing in it, the coil acts like a . . .
|The magnetic field in an electromagnet can be made stronger by . . .
|increasing the current or by using more turns of wire
|A strong electromagnet needs to have a core made of . . .
|If a steel rod is placed inside an electromagnet it will . . .
|become permanently magnetised but only if the coil carries a direct current
|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
|Reversing the current direction in an electromagnet . . .
|reverses the poles Because This is what AC does 50 times a second
|Electromagnets are used in devices called . . .
|circuit breakers ( and relays ) Because When a large current flows, the electromagnet attracts an iron bar which opens a switch
|When a wire carrying an electric current is placed in a magnetic field it may experience a . . .
|The force on a coil of wire in a magnetic field is the principle of the . . .
|electric motor which spins continuously in one direction
|In a simple dc motor, the device which allows it to spin continuously in one direction is called a . . .
|split ring commutator Because It reverses the direction of current every half turn
|If a magnet is moved into a coil of wire which is part of a complete circuit, a current is . . .
|induced Actually a voltage is induced first and then a current flows in the circuit
|If a magnet is moved in and out of a coil, the direction of the induced current will . . .
|reverse Because that is, change from one direction to the opposite direction
|The production of electricity by means of a coil of wire moving in a magnetic field is called . . .
|A device which changes the voltage of an AC supply is called a . . .
|Transformers are used at power stations to . . .
|increase the voltage of the electricity supply to reduce energy losses
|Power lines carry electricity at high voltage because . . .
|this reduces energy losses
|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
|A generator consists of . . .
|a coil of wire rotating in a magnetic field. It produces alternating current
|A transformer can only work with AC because . . .
|it needs a changing magnetic field to induce a voltage in the seconday coil
|If a wire or coil moves through a magnetic field we say it is . . .
|cutting the lines of force
|When a wire cuts through a magnetic field . . .
|a voltage is induced between its ends Because A current will flow if we connect the wire to a complete circuit
|If a coil rotating in a magnetic field is spun faster, the voltage induced will . . .
|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
|An AC generator consists of . . .
|a coil rotating in a magnetic field. Power stations have several of these going at the same time
|The current is taken from a generator by means of . . .
|slip rings and brushes. This prevents sparks ( or tangled wires ).
|The brushes in a generator or motor are usually made from . . .
|graphite ( carbon ) Because It's a good conductor and it's slippery
|A transformer works because . . .
|an alternating current in the primary coil induces another alternating current in the secondary coil
|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
|When an alternating voltage is applied across the primary coil of a transformer . . .
|an alternating voltage is produced (induced) across the secondary coil
|common ferromagnetic materials
|iron, nickel, and cobalt
|the region of Earth's magnetic field shaped by the solar wind
|streams of electrically charged particles flowing at high speeds from the sun
|the region around a magnet where the magnetic force is exerted
|the Northern Lights
|the force of attraction or repulsion of magnetic materials
|easily loses its magnetism
|a cluster of billions of atoms that all have magnetic fields lined up in the same way
|unlike magnetic poles
|attract each other
|like magnetic poles
|repel each other
|magnetic field lines
|never cross; they form complete loops from pole to pole; they spread out as they get farther from the magnet
|where the magnetic force is the strongest
|magnetic properties of a material
|depend on its atomic structure
|every magnet, regardless of its shape,
|has two magnetic poles
|a spinning electron
|produces a magnetic field
|a coil of wire with a current
|a solenoid with a ferromagnetic core
|the relationship between electricity and magnetism
|an electric current produces
|a magnetic field
|the two ends of a solenoid
|act like poles
|the magnetic pole in the Northern Hemisphere is
|in Northern Canada
|one part of a freely swinging magnet always points
|to Earth's magnetic pole in the Northern Hemisphere
|most materials are not magnetic because
|their magnetic domains are arranged randomly
|as Earth's magnetic pole moves,
|the magnetic declination in a given location will change
|you can destroy a magnet's magnetism
|by heating it or by dropping it or by striking it hard
|since Earth produces a strong magnetic field,
|Earth can make magnets
|a magnet made from a steel paperclip is most likely
|a temporary magnet
|a compass behaves as it does
|because of Earth's magnetic field
|Earth's magnetic field can make a magnet out of an iron bar
|by causing the magnetic domains to line up in the same direction
|if you break a magnet in half
|each half will be a new magnet, with both a north and south pole
|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
|uses of an electromagnet include
|lifting heavy metal objects with a crane at a junkyard; recoding a song onto an audiotape; and recording a television show onto a videotape
|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
|is a physical property that we cannot sense
|a proton in motion
|is capable of creating a magnetic field
|is a combination of aluminum, nickel & cobalt; is 1 of the more useful magnets produced from ferromagnetic material; can be permanently magnetized
|is a source of electromotive force
|circuit containing a solid-state diode
|electrons will be permitted to flow in one direction but not the other
|is one of the fundamental forces.
|is a temporary magnet produced by a moving electric current
|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.
|movement of conductor
|magnetic lines of force field
|current or electron flow
|3 ways to induce electromagnetic current flow in a conductor
|1- move the conductor through a unchanging-strength magnetic field; 2- move magnetic lines of force through a stationary conduction with an unchanging-strength magnetic fields; 3- vary the magnetic flux strength from a stationary magnet through
|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
|differences of a generator & motor
|generator converts mechanical energy to electrical energy & a motor converts electrical energy to mechanical energy.
|creates an electrical "one way street" by permitting electrons to flow easily in 1 direction while offering a high resistance to movement in the other direction