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Just a few comments

Discussion in 'A+' started by se99paj, Jun 2, 2006.

  1. se99paj

    se99paj New Member

    I just read the complete thread of this and got a bit confused.

    I think the main problem the difference between AC and DC, please correct me if I'm wrong on any of this.

    The best description for DC is anything fitted with a battery, the charge travels one way around the circuit.

    AC is very different, the current alternates between the live and neutral wire as a sine wave. in the UK we have 230V (I think that means the sine wave travels voltage alternates between + 115V and -115V.)
    Just in case you were wondering why we use AC instead of DC for home electricity its because it is cheaper. Electricity at a high voltage can be distributed around the country and then stepped down to a different voltage at your home using transformers, which is only possible using AC.

    If any of this is completely wrong then just let me know and I will change it.
  2. hbroomhall

    hbroomhall Petabyte Poster Gold Member

    You should really comment on the thread - rather than start another one! It isn't always otherwise obvious what you are talking about.
    Er - no. Look up 'RMS'. :biggrin The 230V measurement is a RMS one. If you do the maths (multiply by √2 - and I'll be interested to see if that sign works!) you get a peak voltage of about 325V, so the wave goes from -325 to +325.

    Certifications: ECDL A+ Network+ i-Net+
    WIP: Server+
  3. Boycie
    Honorary Member

    Boycie Senior Beer Tester

    I would say what you have learned will be fine for A+ :thumbleft
    Certifications: MCSA 2003, MCDST, A+, N+, CTT+, MCT
  4. Baba O'Riley

    Baba O'Riley Gigabyte Poster

    Not strictly true. The reason we step up the voltage of AC to transmit it across the National Grid is because more voltage means less current which means less heat generated so less energy lost which means better efficiency.
    Certifications: A+, Network+
    WIP: 70-270
  5. GW

    GW Byte Poster

    If I remember correctly (It's been 20 years since I read up the history side of it); but at the time when the government and such were deciding on which way to go for national/state electricity, AC could travel longer distance than DC without a repeater or stepping station (or whatever they were calling it) and the AC generators at the time were more reliable than the DC generators.

    But I think AC was considered cheaper than DC because they would have to implement more infrastructure to get the DC electricity to travel longer distances.

    Certifications: MCP x4, CompTia x3
    WIP: Cisco CCNA
  6. Baba O'Riley

    Baba O'Riley Gigabyte Poster

    That's true GW. Another reason was that it's much easier to convert AC to DC (to run our lovely PCs) than it is to convert DC to AC.
    Certifications: A+, Network+
    WIP: 70-270

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