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T.O.C: Current Can Produce Magnetism
Ch. 3; Lesson 3.2 T.O.C: Current Can Produce Magnetism
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Electric Current Produces a Magnetic Field
1800’s- Hans Christian Oersted discovers a connection between electric current & magnetism : Electric current produces a magnetic field which can cause objects to become magnetized Electromagnetism w.w- magnetism that results from an electric current. When a charged particle –electron- moves; it produces a magnetic field. If wire is straight- magnetic field is like a tube around wire, if wire is loop- magnetic field is stronger & is concentrated inside the loop. The more coil, the more concentration → stronger magnetic field Coiled wire w/ charge flowing has magnetic field like a bar magnet. Create coil/wire/bar magnet illustration
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Making an Electromagnet
Electomagnet -w.w. – magnet made by placing a piece of iron or steel inside a coil of wire. As long as the coil carries a current, the metal will act like a magnet & increase the magnetic field of the coil. When current is turned off, magnetic domain in the metal becomes random again & magnetic field/properties are gone. The more coils of wire around metal → stronger electromagnet Some of the most powerful magnets in the world are hug electromagnets used in scientific experiments.
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Uses of Electromagnets
B/c they can be turned on/off, they have more uses than permanent magnets. Ex: Crane in junkyard w/ huge magnet or like the one in the background image move extremely large objects.. Computers use electromagnets to store info ATM/Debit/Credit cards have information in strip swiped at store/bank – don’t store cards w/ strips facing each other b/c the magnetic field can cause info to erase LAB-Build an Electromagnet Labs/Activities section of Notebook- Leave space between each ↓ List materials needed, -wire, iron nail, battery, paper clip How you built your magnet. –build without a switch 1st Make a switch for you electromagnet. Change the amount of coils in your wire- what was your electromagnet with less coils like? With more coils? Change battery sizes- does the size of the battery affect the power of your electromagnet positively, negatively, or not at all?
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Motors use Electromagnets
Electric motors convert the energy of an electric current into motion by using current & magnetism 100’s of devices contain electric motors: blender, mixer, fans, power tools. Almost anything with moving parts that uses current has an electric motor. About Motors Although they may look different in size/appearance, all motors have similar parts & work in similar ways. Main parts of an electric motor: Voltage source, a shaft, and electromagnet, & at least 1 additional magnet. The shaft of the motor turns the other parts of the device. When current from the voltage source flows through the coil, a magnetic field is produced around the electromagnet. The poles of the magnet interact with the poles of the electro magnet, causing the motor to turn. The poles of magnet/electromagnet constantly exert force pushing/pulling each other causing the motor to turn. When the poles line up with their opposites, part of the motor – commutator - reverses the polarity of the electromagnet & the motor keeps turning. The more coils on the electromagnet in the motor, the stronger the motor
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Uses of Motors Motors can move very small objects- like battery operated hands on a wrist watch; or very big, such as the motors that power subway trains. Motors can move objects in any direction. Ex: some motors move objects in circles- CD player, gaming device- & some move objects up/down- power window motors in cars move the windows up/down You can have more than 1 motor in the same device. LAB- Build an Electric Motor
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3.2 Review Q’s (12 pts Explain how electric current & magnetism are related. (2 pts Describe 3 uses of electromagnets. (3 pts Explain how electric energy is converted into motion in a motor. (3 pts How does an electromagnet differ from a permanent magnet? (2 pts What 2 ways can you increase the strength of an electromagnet? (2 pts)
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