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8J Magnetism @ AJHS
magnets and electromagnets
| Question | Answer |
|---|---|
| attract | Two things pulling towards each other. |
| cobalt | A metal that is a magnetic material. |
| iron | A metal that is a magnetic material. |
| magnet | Something that can attract magnetic materials. |
| magnetic materials | Materials that are attracted to a magnet; iron cobalt nickel and steel are all magnetic materials. |
| magnetism | A non-contact force. |
| nickel | A metal that is a magnetic material. |
| north pole | One end of a magnet. This ends points north if the magnet can move. |
| repel | Push away. |
| south pole | One end of a magnet. |
| steel | A mixture made mainly from iron; it is a magnetic material. |
| bar magnet | A straight magnet, shaped like a small bar. |
| compass | A magnetised piece of metal that can swing around – it points north. |
| north-seeking pole | The end of a magnet that points north if the magnet can move freely. Often just called the north pole. |
| south-seeking pole | The end of a magnet that points south if the magnet can move freely. Often just called the south pole. |
| iron filings | Tiny pieces of iron that are sometimes used to find the shape of a magnetic field. |
| 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). |
| plotting compass | A small compass used for finding the direction of a magnetic field. |
| armature | The iron part of a relay that moves when electricity is flowing in the solenoid (or electromagnet). |
| 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. |
| permanent magnet | A magnet that keeps its magnetism – it does not depend on electricity. |
| reed switch | A switch made from two thin pieces of metal, which closes when it is in a magnetic field. |
| relay | A switch that is switched on and off by electricity. |
| solenoid | A coil of wire. |
| core | A solid bar inside an electromagnet – usually made of iron. |
| properties and interactions of magnets | magnetism |
| The collection or flow of electrons in the form of an electric charge | electricity |
| generating electricity with motion | mechanically |
| surrounds an electric charge and exerts a push or pull on other electric charges | electric field |
| charge that collects on the surface of an object | static electricity |
| charge that flows through a conductor | current |
| composed of chemical substances which can generate electrical current | battery |
| electric current running through a wire coiled around a metal core produces this | electromagnet |
| the way most of our electricity is produced | magnetism |
| a machine that converts motion into electricity using magnets | generator |
| what opposite magnetic poles do | attract |
| To strengthen an electromagnet you should (decrease / increase) the number of loops of wire around the nail. | increase |
| In a (parallel / series) circuit electricity can only travel ONE path. | Series |
| The flow electrons is known as _____ | electricity |
| Conductors have _____ resistance. | Low |
| 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) | insulator |
| If you want to produce a large, continuous amount of electricity you need a _____. | Generator |
| 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) | 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 ________ | lightning |
| In a parallel circuit light bulbs can be connected in (a straight line / loops made of wires). | loops made of wires |
| Insulators have _______ resistance. | High |
| In a (parallel / series) circuit electricity can travel MORE THAN ONE path. | Parallel |
| 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) | insulator |
| Copper would be classified as a _______ (conductor / insulator) | conductor |
| 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) | insulator |
| Objects become electrically charged when they gain or lose _______ | electrons |
| 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 ________. | Electrons |
| ALL of the lights connected on a series circuit will (brighter / dimmer) than lights connected on a parallel circuit. | Dimmer |
| 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 ___________. | fossil fuels |
| 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. | Magnet |
| Pull toward each other. | Attract |
| The force or energy that magnets possess. | |
| magnetism | A rock found in the Earth. |
| To push away. | Repel |
| The ends of a magnet. | Poles |
| An object made with a magnet that can help you find your way. | Compass |
| The area around a magnet in which the force of the magnet acts. | magnetic field |
| A south pole and a south pole will... | repel |
| A south pole and a north pole will... | attract |
| an object that has the property of attracting certain materials, mainly iron and steel | magnet |
| A magnet's property of attracting certain materials, mainly iron and steel | magnetism |
| 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 |
| 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 | south pole |
| 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 | magnetic field |
| A naturally magnetic mineral found at or near Earth's surface. | lodestone |
| A device containing a magnetized needle that moves freely and is used to show direction. | Compass |
| a push or pull | force |
| an object that sticks to iron | magnet |
| a specific kind of force | magnetism |
| when magnets pull together | attract |
| when magnets pull apart | repel |
| a piece of iron that behaves like a magnet when it is touching a permanent magnet | temporary magnet |
| the influence of a permanent magnet's magnetic field on a piece of iron, which makes the magnet act like a magnet | induced 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 | two magnets |
| 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)? | electricity |
| 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? | magnetic repulsion |
| What force powers an engine? | controlled explosion |
| 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 . . . | magnetic field |
| 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 . . . | North-seeking pole |
| 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 . . . | bar magnet |
| 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 . . . | soft iron |
| 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 . . . | force |
| 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 . . . | electromagnetic induction |
| A device which changes the voltage of an AC supply is called a . . . | transformer |
| 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 . . . | increase |
| 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 |
| magnetosphere | the region of Earth's magnetic field shaped by the solar wind |
| solar wind | streams of electrically charged particles flowing at high speeds from the sun |
| magnetic field | the region around a magnet where the magnetic force is exerted |
| an aurora | the Northern Lights |
| magnetism | the force of attraction or repulsion of magnetic materials |
| temporary magnet | easily loses its magnetism |
| magnetic domain | 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 |
| the poles | 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 |
| solenoid | a coil of wire with a current |
| electromagnet | a solenoid with a ferromagnetic core |
| electromagnetism | 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 |
| Magnetism | is a physical property that we cannot sense |
| a proton in motion | is capable of creating a magnetic field |
| Alnico | is a combination of aluminum, nickel & cobalt; is 1 of the more useful magnets produced from ferromagnetic material; can be permanently magnetized |
| a battery | 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 |
| Magnetism | is one of the fundamental forces. |
| Electromagnets | 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. |
| thumb pointing | movement of conductor |
| index finger | magnetic lines of force field |
| middle/other finger | 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. |
| Diode | 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 |
Created by:
johncl
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