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downloader
324 posts |
#177276 2008-05-20 02:32 GMT |
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PLEASE HELP!!!! THANKS!!!
1.List three ways in which the amount of electricity from an electric generator can be increased. 2.(a)What is the meaning of DC? (b)List three devices that use DC. 3.(a)What is the meaning of AC? (b)Name two sources of AC. 4.(a)Electricity is supplied to the armature of a generator through brushes and rings. Explain why continuous wires cannot be used for this purpose. (b)All large generators like those used by B.C. Hydro use electromagnets, Whereas bicycle generators use permanent magnets. See if you can think of reason for this difference. 5.If you had a generator supplying electricity to some appliances connected in parallel, would you expect any change in the generator as more appliances are turned on? HELP!!!!!THANKS ALOT!!!!!>"< |
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AbstractCat
359 posts |
#177277 2008-05-20 02:47 GMT |
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1. Increasing the number of coils on the rotar, increasing the magnetic field strength and increasing the speed at which the rotar moves.
2.a. Direct current. b. Mobile phones, battery operated video games, watches (battery). 3a. Alternating current. b. AC generators, hydropowersations, wind energy plants. 4a. Because the armature spins and the wires would get tangled. Also, the rings change the direction of current every half a turn, thus, keeping continuous motion. b. Permanent magnets are not as strong as electromagnets and are harder to control (they dont lose their magnetism when not required). Electromagnets are far stronger and their strength can be altered easily and can be switched on and off accordingly. 5. I am not sure in this one but i think the answer is no. BART |
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StrangerHere
369 posts |
#177278 2008-05-20 04:59 GMT |
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1. Faraday's law implies simply that higher voltages maybe generated [a] by moving conductors more rapidly across lines of flux, by increasing the number of flux lines across which the conductor move, [c] and by increasing both the speed of the conductors and the flux across which they move.
note:magnetic flux is the lines of force between the north or south poles of a permanent magnet or an electromagnet. [d] Adding up coils: When several coils are joined together properly so that they combined effects acts additively, the result is not only increased in voltage, but also voltage pulsations that are not so violent, in other words, the voltage wave becomes smoother as the number of coils are increased. 2. You may check out the meaning of DC here: http://en.wikipedia.org/wiki/Direct_current Battery, Integrated Circuits, Transistors, It is common for semiconductors to have a DC supply. 3. As well as the AC here: http://en.wikipedia.org/wiki/Alternating_current a) Autotransformer or variable AC transformer , b) AC Generator. 4. a) It is not advisable to use continuous wires, because the rotating element which is called the armature can continuously rotates and some are high speed when it's powered by electricity. However if you use wires, the tendency is that the wires will move together with the armature. And so, it is advisable to use brushes, poles and rings, because they are of course stationary. b) The B.C. Hydro use electromagnet, and we know that for electromagnet to work, you have to supply it with electricity, thus, you can control or calibrate how much amount of power you need to use. Whereas the bicycle generators use only permanent magnet because it is more handy to use and bikes doesn't need to produce much high voltage for them to be used. 5. Remember that a parallel circuit is a current divider. And because the total current entering the junction of parallel branches divides up into each of the branches. So, in this case, when you turned on all the appliances and adding up more loads that are connected parallel to the generator, chances are, there will be some changes in the generators current, but the voltages will all be the same for the appliances as well as the generator. |
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SpeedDemon
381 posts |
#177279 2008-05-20 05:47 GMT |
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I see that the previous 2 answers are from master of electrical field. I shall only answer the last Qn#5.
A generator is a source, as long as the end loading change (increases) the output voltage will change (dip). As such, some of the appliances may not power up. Some may operate at lower operating preference (eg a fan will run a little with lesser current and lower voltage) |
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