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ElectromagnetismThe relationship between electric current and magnetis ElectromagnetismThe relationship between electric current and magnetis

ElectromagnetismThe relationship between electric current and magnetis - PDF document

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ElectromagnetismThe relationship between electric current and magnetis - PPT Presentation

3 2 Electromagnetism OCABULARYRemember to record currentcarrying wire currentcarrying wire Uses of ElectromagnetsBecause electromagnets can be turned on and offthey have more usesthan permanent mag ID: 375125

3 2 Electromagnetism OCABULARYRemember record current-carrying wire current-carrying

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3 2 ElectromagnetismThe relationship between electric current and magnetism plays animportant role in many modern technologies.is magnetism that results from an electric current.When a charged particle such as an electron moves,it produces a magnetic field.Because an electric current generally consists ofmoving electrons,wire produces a magneticfield.In fact,the wire acts as a magnet.Increasing the amount ofcurrent in the wire increases thestrength ofthe magnetic field.ou have seen how magneticfield lines can be drawn arounda magnet.The magnetic fieldlines around a wire are usuallyillustrated as a series ofcircles.The magnetic field ofa wireactually forms the shape ofa tube around the wire.Thedirection ofthe current determines the direction ofthe magnetic field.the direction ofthe electric current is reversed,the magnetic fieldstill exists in circles around the wire,but is reversed.the wire is shaped into a loop,the magnetism becomes concen-ated inside the loop.The field is much stronger in the middle oftheloop than it is around a straight wire.Ifyou wind the wire into a coil,the magnetic force becomes stronger with each additional turn ofwireas the magnetic field becomes more concentrated.A coil ofwire with charge flowing through it has a magnetic fieldthat is similar to the magnetic field ofa bar magnet.Inside the coil,the field flows in one direction,forming a north pole at one end.The flow outside the coil returns to the south pole.The direction ofthe electric current in the wire determines which end ofthe coilbecomes the north pole.Check Your Reading Electromagnetism OCABULARYRemember to record current-carrying wire current-carrying wire Uses of ElectromagnetsBecause electromagnets can be turned on and off,they have more usesthan permanent magnets.The photograph below shows a powerfulelectromagnet on a crane.While the electric charge flows through theils ofthe magnet,it lifts hundreds ofcans at a recycling plant.Whenthe crane operator turns offthe current,the magnetic field disappearsand the cans drop from the crane.A permanent magnet would not be nearly as useful for this purpose.Although you could use a large permanent magnet to lift the cans,itould be hard to remove them from the magnet.ou use an electromagnet every time you store information on amputer.The computer hard drive contains disks that have billionsoftiny magnetic domains in them.When you save a file,a tiny electromagnet in the computer is activated.The magnetic field oftheelectromagnet changes the orientation ofthe small magnetic domains.The small magnets store your file in a form that can be read later bythe computer.A similar system is used to store information on mag-netic tape ofan audiocassette or videocassette.Sound and pictures arestored on the tape by thearrangement ofmagnets embedded in theMagnetic information is often stored on credit cardsand cash cards.A black strip on the back ofthe card ntains information about the account number andpasswords.The cards can be damaged ifthey are fre-quently exposed to magnetic fields.For example,cardsshould not be stored with their strips facing each other,ornear a magnetic clasp on a purse or wallet.These magneticfields can change the arrangement ofthe tiny magneticdomains on the card and erase the stored information. wire currentelectromagnet off to collect and move MAIN IDEA WEBelectromagnets. The electromagnetÕs poles are sourceelectromagnet magnet the electromagnetÕs poles to How a Motor WorksAlthough motors may look different from each other,they all have similar parts and work in a similar way.electromagnetshaft motor in fan 1 2 3 on each other.