Alternating current versus direct current

  1. i am currently going over ac and dc currents in school but i want to know more but my teacher isnt going very deep into this subject. Can you help me out please?
     
  2. jcsd
  3. turbo

    turbo 7,366
    Gold Member

    Try using Google for the basics, then re-post if you don't get the help that you want. This stuff is pretty basic, and it would take a WHOLE lot writing to explain it all, especially since you haven't been very specific about what you need to know.
     
  4. well what i want to know is what appliances use ac and dc and how they are generated
     
  5. turbo

    turbo 7,366
    Gold Member

    You are asking a very trivial question that you can research with Google in a matter of minutes. Please make some effort on your own, come back here and demonstrate that you have made the effort, and tell us your understanding of the situation. Then, I will be happy to help clarify your understanding, if necessary.
     
  6. well i found out that dc flows in 1 direction and is useed by cpus, micro electronics,recharging storage batteries.

    and that ac goes 1 way then goes the other way 60 times a second and that is can be generated by wind, water, nuclear, oil, and that the generators use magnets and that ac is used in power outlets.

    but i just cant find how DC is GENERATED i googled it several times with different key words but it comes out with stuff too complicated for me to write and if i do my teacher will suspect something b/c im in the 8th grade so can any1 help me with that like give me a website that explains that part??
     
  7. turbo

    turbo 7,366
    Gold Member

    HINT!!!! You can smooth and rectify AC to produce DC. Pay attention to "rectification" because that word will be your friend. Good luck!
     
  8. thanks for the hint but i dont see how that explaines how dc is produced
     
  9. turbo

    turbo 7,366
    Gold Member

  10. oh come on, i'm not that smart im only 14!!! our probe classes havent even tapped into rectification!
     
  11. well does anyone know how DC can be generated from AC?
     
  12. turbo

    turbo 7,366
    Gold Member

    halfANDhalf, if you ever expect to understand electronics, you have to grasp the concept of rectification. I can't spoon-feed it to you unless I want to spend hours and hours explaining it. Please Google it. Hint: Turbine-generator sets are designed (with rectifier circuits) to charge the batteries that are used to "flash" the generator on start-up to create a field that can be used to get the generator producing power. Every large generating station uses both AC and DC power to do their magic. I understand that you are only 14, but when I was a child, I lived in a tiny town with a very large hydro-dam and the operators knew me and allowed me to visit the power-plant from time to time. The battery-room (all DC) of a large hydro-dam can be huge and daunting!

    I understood field flashing 'way before I was 14 - at least on some level.
     
  13. oh ok thanks but when u said if i want to understand electricity i need to know ratification or wahtever i just dont know that far into electricity so when i get there i will better understand what you said
     
    Last edited: Apr 14, 2008
  14. never mind i found it out it means : conversion of alternating current to direct current right? thank you
     
  15. turbo

    turbo 7,366
    Gold Member

    Listen! You can take alternating current and run it through a tube rectifier or through a capacitor-based rectifier and make DC out of it. It's also possible to produce DC that has AC-like ripples.

    Study! Please take the time to research electricity and learn - then come back with questions. If you are serious about learning, I will help you, and others will, too. If you keep posing general questions about very basic concepts, people will ignore your posts and you will not benefit.
     
  16. Astronuc

    Staff: Mentor

    As Turbo indicated - rectification. Please show some effort by oneself.

    For small voltages and currents, simple diodes are used in a diode bridge, but for large power systems, silicon controlled rectifiers (SCRs) are necessary. Also, its better to use multiple phases, with each phases out of phase, such that as the voltage of one phase is decreasing, the voltages of the other phases are increasing.

    This site might be helpful for understanding electronics and electrical theory.
    http://www.allaboutcircuits.com/vol_2/index.html
    http://www.allaboutcircuits.com/vol_3/index.html


    An alternative method, and less efficient would be to use an AC motor to drive a homopolar generator (HPG).
     
  17. the best thing to do is to buy a book.
    i've found the internet pretty good for buying stuff
    and communications and entertainment.

    pretty darn useless for learnin about anything
    [with sites like this an exception of course! :p]

    in college when i wanted to know something i'd sometimes spend 1~2 hrs googleing etc etcetc and not get very far.

    then i'd go to the library, spend 10 mins finding the right shelf!
    20~30 mins finding the right book.
    and then another half hour or more reading.
    ppl get paid to write books, the internet is free. you usually get what you pay for.
    for the basics and broad, [introductions] buy a book and read it.
    for specifics or opinions or ideas use forums!

    almost every subject in the world has many many books written on it.
    and most of theese are titled

    "bla bla bla", An Intoduction to "bla"
     
  18. turbo

    turbo 7,366
    Gold Member

    Oops! I didn't review before posting. Common SS rectification circuits are made up of diodes, not capacitors. Capacitors are used to take out the ripples and smooth the DC after it is produced. This was common in guitar amplifiers from the '60's on. Until the '60's most amps used rectifier tubes but as the power-handling and reliability of diodes improved, diodes often got the nod. Since diodes *can* fail under reverse bias, they were often used in series. IIR, the Fender Twin Reverb design employed series chains of 3 diodes on each leg of the rectifier circuit.
     
    Last edited: Apr 15, 2008
  19. i already found that stuff out now besides i already looked it up bnut thanks any ways you guys really help out on my exam
     
  20. turbo

    turbo 7,366
    Gold Member

    We will ALWAYS help if you come here having covered the basics on your own and want help with the details. Everybody here who helps with homework and studies is volunteering their time for free and we all have jobs, school, research, families, etc that take up much of our time, so we appreciate it when students with questions will do as much independent work as possible and then pose questions when they hit a snag. If it were not done this way, we couldn't help anywhere near as many people.
     
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