* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Magnetism: Book ch 36
Three-phase electric power wikipedia , lookup
History of electromagnetic theory wikipedia , lookup
Variable-frequency drive wikipedia , lookup
Brushed DC electric motor wikipedia , lookup
Buck converter wikipedia , lookup
Stray voltage wikipedia , lookup
Transformer wikipedia , lookup
Switched-mode power supply wikipedia , lookup
Opto-isolator wikipedia , lookup
Wireless power transfer wikipedia , lookup
History of electric power transmission wikipedia , lookup
Voltage optimisation wikipedia , lookup
Mains electricity wikipedia , lookup
Power engineering wikipedia , lookup
Electrification wikipedia , lookup
Electric machine wikipedia , lookup
Magnetic core wikipedia , lookup
AC/DC/e-m quiz Review all 4 ppts on my website: AC/DC, ACpower awesome, electricity and magnetism, AC DC Tesla Book work: AC/DC Ch 34: rev questions 18-25 E-M Ch 36, sections 1-5, 9: o rev questions 1-5, 10, 11,19 1. They attract and repel one another 2. Can isolate or separate charges, not poles 3. Space around magnet or moving charges that can exert a force; source is moving electrons 4. Electrons spin in opposite directions, fields cancel 5. Fields of iron’s electrons do not cancel entirely 10. Concentric circles 11. Fields overlap, add up as vectors inside the loop, they can partially cancel outside the loop 19. Currents in the earth’s molten layer o think & explain 1, 5, 9 o o o 1. Electric field surrounds any electric charge; electric AND magnetic field surrounds a moving charge 5. Question relates to the electromagnet used in scrapyards to move junk cars and scrap metal: iron inside the coil or loop may be a magnet already or becomes magnetized when the current in the coil around it is turned on; it multiplies, increases the mag field from the coil alone 9. Pigeons can sense the earth’s magnetic field Ch 37, sections 1-6: o rev questions 1-3, 7-10, 14, 17, 18 o o o o o o o o o o 1. Magnet in motion can induce voltage, current in a wire 2. Wire and magnet must be in relative motion; the magnetic field must be changing! 3. More loops, more voltage, current induced 7. Generator requires mechanical energy or work in to transform into electrical energy Motor takes electrical energy, transforms into mechanical energy 9. What causes rotation of the coil/magnet? Work by some external method such as spinning turbines using wind, water, combustion of fossil fuels 10. 3 main ingredients of motor are same as for generator: magnetic field, moving charges, magnetic force. 14. Ste-up transformer steps up VOLTAGE 17. Power in = power out, IV in = IV out, if no energy, power losses 18. High voltage = lower current = lower power losses over long distances o think & explain 8-11 8. If you move a magnet so that it doesn’t change the field through the cross section of the coil/loop 9. Transformer needs AC because AC provides the changing magnetic field needed to induce a voltage, current in the other part of the transformer 10. Transformer can produce more energy than goes in, power in= power out of 100% efficient, can’t step up energy, goes against conservation of energy 11. Can’t connect motor to generator in a closed circuit and expect it to run forever = perpetual motion machine, there will be losses due to < 100 % eff, Light quiz Review waves, light ppts and documents on my website Please check the ‘light lab’ document on my website. It lists relevant sections in the book for each of the 11 labs we did.