* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Electromagnetism - Physical Science
Wireless power transfer wikipedia , lookup
Three-phase electric power wikipedia , lookup
Magnetic field wikipedia , lookup
High voltage wikipedia , lookup
National Electrical Code wikipedia , lookup
Multiferroics wikipedia , lookup
Insulator (electricity) wikipedia , lookup
Electromagnetism wikipedia , lookup
Magnetoreception wikipedia , lookup
Induction heater wikipedia , lookup
Electromotive force wikipedia , lookup
Magnetochemistry wikipedia , lookup
Electrical resistance and conductance wikipedia , lookup
Magnetohydrodynamics wikipedia , lookup
Electricity wikipedia , lookup
Hall effect wikipedia , lookup
Lorentz force wikipedia , lookup
History of electromagnetic theory wikipedia , lookup
Superconductivity wikipedia , lookup
Friction-plate electromagnetic couplings wikipedia , lookup
Electric current wikipedia , lookup
Faraday paradox wikipedia , lookup
Skin effect wikipedia , lookup
Electrical injury wikipedia , lookup
Electric machine wikipedia , lookup
Force between magnets wikipedia , lookup
History of electrochemistry wikipedia , lookup
Scanning SQUID microscope wikipedia , lookup
Magnetic core wikipedia , lookup
Eddy current wikipedia , lookup
Alternating current wikipedia , lookup
Magnetism(Review) Magnetic Field Lines always move out of the __________end of a magnet! A. B. C. D. East North South West Magnetic Field Lines always move into the __________end of a magnet! A. B. C. D. East North South West Where are all magnets the strongest? A. B. C. D. At the North Pole At the South Pole At both Poles Directly in the center Magnets can be made of iron, _________, or nickel. A. B. C. D. Copper Carbon Cobalt Cadmium Two similar poles of a bar magnet will always _____________. A. attract B. repel Two opposite poles of a bar magnet will always _____________. A. attract B. repel Electromagnetism --the relationship b/w electricity and magnetism Is there a relationship between electricity and magnetism? Let’s see what I discovered!!! Hans Christian Oersted Oersted’s Law • The flow of electricity through a wire conductor produces a magnetic field around the wire. Right Hand Rule • The direction of the current determines the direction of the magnetic field. Can anything affect the strength of a magnetic field? 2 things affect the strength of a magnetic field: • Amount of current • # of coils of wire – Increase current = increase strength – Decrease current = decrease strength – More turns of wire = more strength – Less turns of wire = less strength I was just wondering what would happen if I slammed an iron core through a current carrying coil of wire? What did you find out? If you take an iron core and insert it into a coil of current carrying wire, you have a temporary magnet called an electromagnet!! Strength of an Electromagnet • 2 things affect the strength of an electromagnet(same 2 things that affect the strength of a magnetic field): 1. Amount of Current 2. # of turns of wire(# of coils) What happens to the strength of an electromagnet if the current through the wire increases from 4 A to 9 A? A. Remains the same B. Increases C. Decreases Which electromagnet will be the strongest? A B Uses of Electromagnets • Electric Meters: because of their ability to detect current(only work when there is one), electromagnets are used in a variety of electric meters. 1. Ammeter—measures current • Wired in series 2. Voltmeter—measures voltage • Wired in parallel 3. Galvonometer—”detects” current Uses of electromagnets(cont.) • Motors – Use electromagnets to convert electrical energy into mechanical energy – An electromagnet turns inside a permanent magnet Motors If current moving through a wire produces a magnetic field, I wonder…… ….What would happen if we move a wire through a magnetic field I bet it has never been tested. Let’s try it!!! I’ll try anything once!! Haven’t we already done that? Joseph Henry Michael Faraday Faraday and Henry discovered that moving a wire through a magnetic field, or moving a magnetic field through a coil of wire “induced” a current on the wire!! Electromagnetic Induction— process in which moving a wire through a magnetic field produces a current on the wire. ….produces a current on a wire. “Did we just “create” electricity” • Generators—use electromagnets to convert mechanical energy into electrical energy. Generators Other Uses of electromagnets: Transformers Not this Kind!!!! Are you talking about me? Alternating vs. Direct Current Alternating Current • Current alternates, one direction, then the other. Plug it in, Plug it in!! Direct Current • Current only goes in one direction. Transformers •Used to increase or decrease the voltage of alternating currents. Transformers • Consist of 2 coils of wire. – Primary Coil • Alternating current enters – Secondary Coil • Alternating current leaves • It’s the difference in the number of turns of wire on each coil that causes the voltage the change. 2 Types of Transformers • Step-up Transformer – Increase voltage – Secondary more turns than primary • Step-down Transformer – Decrease voltage – Primary more turns than secondary Math of a Transformer: A step-up transformer has 400 turns on its primary coil and 600 turns on its secondary coil. If the primary coil is supplied with 120 V of alternating current, what will be the secondary (output) voltage? ns= 600 turns np= 400 turns Vs= ? Vp= 120 Example #2 Example #3