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| Thread ID: 63498 | 2005-11-11 16:50:00 | electonics | chel (9230) | PC World Chat |
| Post ID | Timestamp | Content | User | ||
| 403599 | 2005-11-11 16:50:00 | anyone help me..... what are the kinds of current aside from ac and dc? and also the kinds of voltage..... please help me...... |
chel (9230) | ||
| 403600 | 2005-11-11 17:41:00 | Is this a practical problem or an exercise in theory? Perhaps you should try putting your questions into a search engine like Google so that you can filter the answers according to your needs. | PaulD (232) | ||
| 403601 | 2005-11-11 22:28:00 | Have a look here: www.gcse.com Current is a flow of charges, either electrons in metals or ions in fluids. The word 'fluids' means gases as well as liquids. There is only one 'kind' of voltage. Voltage is a measure of potential energy difference causing the charges to flow. Is that what you are looking for? |
Terry Porritt (14) | ||
| 403602 | 2005-11-11 23:15:00 | As far as I know there is only AC & DC, There is RF but then that is high frequency AC As for Voltage, the other one is static electricity, not a lot of use to anyone, that's what causes car sickness, and when you rub nylon & wool together and lightning strikes. |
Eric Richards (6226) | ||
| 403603 | 2005-11-12 00:55:00 | As Terry has said, in the electrical sense, current is simply the flow of electrons and the strength of that flow or the form it takes is dictated by the application . Alternating current (AC) is most commonly used for electrical power supply and distribution . The frequency of alternation is 50Hz in NZ, Australia, and most European countries, and 60Hz in America, Japan and any other countries where the US has had a significant influence in commercial or industrial development . AC normally has a sine waveform, and radio-frequency carriers are also sinewave . It is called alternating current because the voltage polarity varies in the positive and negative directions about its zero crossing point, and the current flow reverses for each half-cycle . DC is direct current, usually from batteries or from rectified AC and is most commonly used for operating electronics and for some industrial processes . Some high-voltage power reticulation is DC, as in the link between the South and North Islands of NZ . Outside of power reticulation and RF carriers, there are as many waveforms for electrical current as Mans' ingenuity can devise, and similarly the modulation of information onto an RF carrier also has as many waveforms as technology may require . Voltage is the potential difference or voltage "pressure" that drives the current and is measured in volts . Once again, there are as many levels of voltage as Mans' ingenuity and electrical needs may dictate, from nano-voltages up to many millions of volts (megavolts), though domestic AC power is usually 110-120 volts ac for 60Hz supplies, and 220-240 volts ac for 50 hz supplies . Provided it always remains positive (or negative) in relation to its reference or ground point, it is by definition a DC voltage and will produce a direct current, that is to say, a flow of electrons in one direction only . The voltage applied to any open circuit system could be called static, because no current is flowing, but "static electricity" as mentioned by Eric relates mainly to the means of generation, because the range of "static" voltages is again from nanovolts to megavolts, though we only pay attention to that when we get zapped by a static charge, or see a lightning strike . So, to summarise the answer to your question, there are really only two types of current, direct or alternating, and the level of current flow and the waveform characteristics have a virtually infinite number of variations . The same applies to voltage . In simple terms it is defined as the pressure that drives the current, however there are an infinite number of voltage levels and waveform characteristics for a voltage driving a direct current, and the same applies for alternating currents . That's as simple an explanation as is possible, while still covering all of the variations that may be encountered . Cheers Billy 8-{) |
Billy T (70) | ||
| 403604 | 2005-11-12 01:19:00 | I was being very basic from a physics point of view, not distinguishing between steady electron flow and time dependent flow, whereas Billy and Eric have amplified into applied situations, and say that AC and DC are 2 types of current, it's just a different viewpoint. But I'd still say there are 2 types of current, electron flow (whether steady or changing in some way eg AC), and ionic flow in fluids, again either steady or varying with time. I suppose we could also talk of flow of 'holes' in semi-conductors :) From a physical point of view, whether voltage varies with time, as in an alternating domestic supply, or whether we are looking at static electricity, it is still just a measurement of energy from a reference level. So from that view point there is just one kind of voltage. I'm taking a leaf out of Grahams book and being pedantic :) |
Terry Porritt (14) | ||
| 403605 | 2005-11-12 02:43:00 | sounds like a homework question to me | drcspy (146) | ||
| 403606 | 2005-11-12 04:00:00 | sounds like a homework question to me Yes, I figured that! There was potential depth in the question though, so I left plenty for research.:D I notice he/she hasn't been back yet, at least not with further questions. Cheers Billy 8-{) |
Billy T (70) | ||
| 403607 | 2005-11-13 17:21:00 | There is another type of Voltage "re-Volting" If you go to this web site http://www.tv3.co.nz/ you will see it will give you the energy to vomit. |
Eric Richards (6226) | ||
| 403608 | 2005-11-13 18:18:00 | You have a very weak stomach and a low tolerance threshold if TV3's website makes you feel that bad Eric. I can't really see your point, or the relevance of the post to this thread. :confused: Cheers Billy 8-{) :help: |
Billy T (70) | ||
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