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Electrical circuits

  1. Feb 1, 2012 #1
    1. The problem statement, all variables and given/known data


    1. How do you expect the frequency generator output voltage to change with increasing load (decreasing
    impedance)?

    2. Explain the meaning of component tolerance. (E.g. Tolerance of a resistor)

    3. Is a real inductor completely reactive? Why

    2. Relevant equations

    V = IR ?

    3. The attempt at a solution

    I don't think I know what a frequency generator is so im pretty much lost on part 1

    Tolerence of a resistor is the limit it is rated for so 1kOhm will burn up if anything higher is forced through it

    For part 3 I don't know what they mean by reactive?
     
  2. jcsd
  3. Feb 1, 2012 #2
    We know that an inductor has ideally zero resistance. It merely stores energy from the circuit, and then returns it back to the network. This is ideal. What would make it not ideal, and therefore real (ie. real life)? It's meant to not dissipate energy, merely transfer it. Any ideas?
     
  4. Feb 3, 2012 #3

    vk6kro

    User Avatar
    Science Advisor

    A frequency generator is a (usually) nice looking box with a knob on the front of it for varying frequency and another knob for varying the output voltage. They can be cheap ($50) or expensive ($5000) depending how good they are.

    The output is a sinewave or a square wave or possibly a triangle wave. These often have an internal resistance of 50 ohms and this is effectively in series with the output.

    This should be enough to answer question 1.

    Component tolerance is not what you describe. I think you were describing power rating or voltage rating.
    I might say I need a resistor of 1000 ohms with a tolerance of 10%
    That means I need a resistor whose actual resistance is between (1000 - 10% or 900 ohms) and (1000 + 10% or 1100 ohms).

    Reactance is the equivalent of resistance for Inductors (coils) and capacitors.
    In each case, it varies with frequency.
    They have this property and draw current related to it, but they return the current to the supply on each half cycle of the supply waveform, so there is no net loss of power because of it.
    You could read this article about it:
    http://en.wikipedia.org/wiki/Electrical_reactance
     
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