Magnetism and Electromagnetism. MAGNETISM DAY 1 What causes magnetism? How is magnetism linked to electric charges? Magnetic fields come from moving.

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    24-Dec-2015

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<ul><li> Slide 1 </li> <li> Magnetism and Electromagnetism </li> <li> Slide 2 </li> <li> MAGNETISM DAY 1 </li> <li> Slide 3 </li> <li> What causes magnetism? How is magnetism linked to electric charges? Magnetic fields come from moving charges a moving charge around an atom produces a magnetic field currents in wires will produce magnetic fields The opposite is also true: moving magnetic fields will cause charges to move (electromagnetic induction) </li> <li> Slide 4 </li> <li> What causes magnetism? How is magnetism linked to electric charges? Magnetic forces are NOT the same as electric forces. How are they the same? Like poles repel. Unlike poles attract. How are they different? Magnetic poles always come in pairs. You cant separate a North from South pole. </li> <li> Slide 5 </li> <li> Slide 6 </li> <li> Slide 7 </li> <li> Domains and magnetism magnets an object that has an alignment of domains due to alignment of atoms and their magnetic dipoles ferromagnetic materials (like iron) can become magnetic near a magnet because the domains line up </li> <li> Slide 8 </li> <li> Magnetic Poles magnetic pole where the magnetic field is strongest like poles repel (North repels North and South repels South) unlike poles attract (North attracts South) </li> <li> Slide 9 </li> <li> Properties of Magnets cut a magnet in half and you get two magnets that still have a north and south pole heat it up or bang it around and you weaken the magnet by jumbling domains Make a magnet by passing current through iron (line up domains) </li> <li> Slide 10 </li> <li> Earths magnetic field Earth has a magnetic field because of a rotating iron core So why does a North pole of a compass point North? Because the Earths magnetic south pole is located in geographic North </li> <li> Slide 11 </li> <li> Moving charged particles </li> <li> Slide 12 </li> <li> Slide 13 </li> <li> Right Hand Rule #1 *Thumb in direction of current *Fingers show how the magnetic field wraps around the wire </li> <li> Slide 14 </li> <li> What does the magnetic field look like around this wire? </li> <li> Slide 15 </li> <li> Right hand rule #2 Force on a moving charge Units: Tesla (T) Thumb = v = velocity of + charge (conventional current) Fingers = B = direction of magnetic field Palm = F = force on charge X = into the page = out of the page </li> <li> Slide 16 </li> <li> A positive particle is fired to the right through a magnetic field directed into the page. What is the resulting force on the particle? Magnetic field into board + v v FBFB + + ++ + + Note speed never changes; this causes the particle to curl. Force is always to v </li> <li> Slide 17 </li> <li> What will be the direction of the magnetic force on this proton? </li> <li> Slide 18 </li> <li> Slide 19 </li> <li> 2 nd Right hand rule </li> <li> Slide 20 </li> <li> A loop of wire is held inside a magnetic field directed into the page as shown. The movable bar is dragged to the right with a speed v. What is the direction of the current in the loop? </li> <li> Slide 21 </li> <li> MAGNETISM DAY 2 </li> <li> Slide 22 </li> <li> Electromagnet electric current creates a magnet making an electromagnet wrap a current carrying wire around iron core and it will set up a north and south pole </li> <li> Slide 23 </li> <li> Electromagnetic induction Reviewso far weve seen that a moving charge (a changing electric field) produces a magnetic fieldthe opposite is also true. Faradays Law A changing magnetic field will induce a voltage in a wire (and a resulting current) </li> <li> Slide 24 </li> <li> Slide 25 </li> <li> Three every day Items that use electromagnetic induction Electric Motors Electric Generators Electric Transformers </li> <li> Slide 26 </li> <li> Electric motors Electromagnet in a magnetic field will rotate electrical energy used to produce mechanical energy </li> <li> Slide 27 </li> <li> Electromagnet making an electromagnet wrap a current carrying wire around iron core and it will set up a north and south pole </li> <li> Slide 28 </li> <li> Electric motors Electromagnet in a magnetic field will rotate (kinetic energy) electrical energy is used to produce mechanical energy </li> <li> Slide 29 </li> <li> Electric motor Commutator ring Commutator allows the current in the electromagnet to switch directions so the motor shaft spins continuously </li> <li> Slide 30 </li> <li> Electric Generator Uses mechanical energy to rotate wires in a magnetic field to produce electrical energy Coil flip-flops so this produces an Alternating Current (AC) in the wire Burn coal or use nuclear power to create steam from water to turn coils Wind and water just turn the turbines directly Something has to turn the coils </li> <li> Slide 31 </li> <li> Electric Transformers Alternating electrical current on one side produces a magnetic field which induces a voltage in the other side of the transformer Steps up voltage with more windings on other side Steps down voltage with fewer windings on other side Power and energy are conserved! Remember, you cant make more energy. </li> <li> Slide 32 </li> <li> Putting it all together Spinning turbines and generators are inside this power plant </li> <li> Slide 33 </li> <li> Electromagnet making an electromagnet wrap a current carrying wire around iron core and it will set up a north and south pole </li> </ul>

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