Inductance and Capacitance

Discussion in 'General Electronics Chat' started by tony8404, Feb 25, 2009.

  1. tony8404

    Thread Starter Active Member

    Jun 11, 2008
    98
    0
    Sorry everyone i decided to rewrite this.

    I really have a question about transformers... Why does, High Voltage - Low Current and Low Voltage - High Current?

    What i was just reading it shows a picture of two transformers, it has the smaller transformer with low voltage-high current and the big transformer High voltage-low current labelled in the picture but in the text does not explain why that is... I know alittle bit about transformers but not following this right now.. I still have some reading but this is bothering me lol thanks
     
    Last edited: Feb 25, 2009
  2. wr8y

    Active Member

    Sep 16, 2008
    232
    1
    I am of the firm belief that you cannot understand inductance and capacitance WITHOUT an understanding of reactance and impedance.

    My suggestion (after 28 years in component-level RF troubleshooting, a CETsr, an Extra Amateur license and an ASEET) is to not be afraid to move on now.

    You can always come back to basics if needed - electronics isn't quite like Math where you have GOT to get things down about 100% before moving on.

    Be encouraged! (And do NOT forget to look EVERYWHERE for the explanation of the same topic. I read ARRL, RSGB and Bill Orr books when studying - as well as my college textbooks when trying to learn something. Sometimes, someone will explain something that will "click" in your mind when you have read someone else's input that didn't make sense before.)
     
  3. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
  4. tony8404

    Thread Starter Active Member

    Jun 11, 2008
    98
    0
    Sorry everyone i decided to rewrite this.

    I really have a question about transformers... Why does, High Voltage - Low Current and Low Voltage - High Current?

    What i was just reading it shows a picture of two transformers, it has the smaller transformer with low voltage-high current and the big transformer High voltage-low current labelled in the picture but in the text does not explain why that is... I know alittle bit about transformers but not following this right now.. I still have some reading but this is bothering me lol thanks
     
  5. tony8404

    Thread Starter Active Member

    Jun 11, 2008
    98
    0
    lol, I know about step up and step down but i am confused i thought high current = high voltage and low current = low voltage. I thought i read that current is proportional to voltage
     
  6. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    Here is a page with transformer theory.
    http://sayedsaad.com/fundmental/index_transformer.htm

    The link comes from this page on transformers from the EDUCYPEDIA.
    http://educypedia.karadimov.info/electronics/electricitytransformers.htm

    There are links for other components too.

    Passive semiconductors technology: Batteries Diodes Photovoltaic systems Switches Buzzers Diode types Quartz crystals Thermoelectric Capacitors General overview Relays Transformers Capacitor types Heat Sinks Resistors Transformers-RF Coils Photo diode Resistors-Nonlinear Transformer types
    Greetings,
    Bertus
     
    Last edited: Dec 31, 2011
  7. ron_o

    New Member

    Mar 1, 2009
    6
    0
    tony8404,
    The answer to your question has nothing at all to do with inductance or reactance (Unless I misunderstood you, why did you title your post that way?) The answer is in the relation between Current and Voltage. The only formula you need to look at is:

    P = E X I

    The relationship between Voltage and Amperage changes in regards to certain static elements in an electric circuit. For Ohm's Law (I=E/R) when resistance stays the same (and in almost every circuit it does stay basically the same) Voltage and Current are directly proportional. Just stick in the numbers and you'll see that is correct. However, in regards to a transformer, power will stay the same (resistance changes in a transformer), and thus Voltage and Current will become indirectly proporional. The voltage/current relationship is relative to Power or Resitance.

    Transformer ---> Power in = Power out (less efficiency)

    When you increase the voltage and power stays the same, then your current *must* decrease in size and vice-versa. This is the fundamental quality that makes A/C so attractive to the entire world. Reducing amperage means a smaller wire (for the same amount of work) and also less voltage drop.

    Just remember to always, always follow what the formula tells you when something doesn't make sense. Plug in the formula and you'll soon realize what happens in an electrical circuit.

    There may seem like there are some contradictions to this but there isn't. Another imporant formula in this regard is

    Power = the square of Voltage / Resistance
    ( http://www.allaboutcircuits.com/vol_1/chpt_5/5.html ).

    The less the voltage in a given circuit when resitance stays the same (as it almost always does) the less the power. This answers the question as to what happens when you hook up 120 volts to a 240 volt utilization equipment. Your Power will actually be cut proportional to the square of the Voltage. In real world terms that means it won't be as efficient if it works at all. (I only mentioned this because there are many electricians who confuse the Voltage and Current relationship with regards to transformers and regular circuits.)

    BTW, my name's Ron. This is my first post. Hehe, I just had to register and answer this one. :)
     
    Last edited: Mar 1, 2009
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