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  1. R

    LPF and HPF

    OK, I will, but first lets make the equation a little more clear. Ic = C*D(Vc,t), where D(Vc,t) means the derivative of Vc with respect to "t". Now, if the charge passed through the capacitor, then the voltage would be constant like a resistor, and D(Vc,t) would always be zero. That would...
  2. R

    LPF and HPF

    Network analysis or circuit theory are not in conflict with the physics of the capacitor. A capacitor has its unique and particular differential equation description due to its property of not allowing any electrical charge to flow through its dielectric. It instead allows the charge to...
  3. R

    Did I pass my exam????!

    Your second answer is correct. It is a simple algebraic manipulation to find the answer. The first answer is wrong, because you can see that the curve is dropping 40 db per decade. Therefore there must be a s^2 term in the denominator when there are no s terms in the numerator. The second...
  4. R

    LPF and HPF

    I cannot comment on something to which I do not have access. However, you must know that a capacitor cannot allow any charge to pass through it. Otherwise it could not accumulate energy by producing a electrostatic field. That's a shame, but I understand. You talked about "current through...
  5. R

    LPF and HPF

    The model has to be based on the physics of the component, otherwise it has no relationship with the component. Any capacitor model has to acknowledge a discontinuity of current in a capacitor. Otherwise, the capacitor would just be a resistor, and would not store energy in a electrostatic...
  6. R

    LPF and HPF

    I am having a hard time understanding your "question". What does HPF and LPF mean? Is it high or low power factor, high or low possible frequency, or maybe even high or low pass filter? It is good practice to fully write out unfamiliar acronyms one time at first. Assuming that you are...
  7. R

    LPF and HPF

    Both time and frequency analysis are mathematical methods which do not supplant the physics of circuits containing electrical components. Whether the charge passes through components like inductors and resistors, or accumulates and depletes on the plates of a capacitor makes no difference in...
  8. R

    LPF and HPF

    Keep in mind that current does not pass through a capacitor. The rate of charge imbalance on the plates simulates the presence of a current in the capacitor circuit. Ratch
  9. R

    Basic question - current

    It is a higher energy density of charge carriers (voltage) and a conduction path that will move the charge carriers. The term "high charge" is meaningless. In a metallic conductor like a wire, there is an ocean of charge carriers (high charge amount of electrons) available. When ever an...
  10. R

    Basic question - current

    Whatever supplies the voltage, be it a battery, generator, or electronic power supply is irrelevant. The voltage source will send out charge carriers from one terminal and receive the same number of charge carriers at the opposite terminal. I sense that you do not understand what voltage is...
  11. R

    induction...

    Are you writing a blog or asking a question? I don't see any question marks in your above discourse. In fact, the whole post seems to be rambling, disjointed, and discombobulated. What, specifically, are you asking about? It does very little good to rattle on about how you plan to apply...
  12. R

    How a BJT Transistor works (base current version)

    I believe we all know the differences between the Ic, Ib, and Ic currents. You made the statement about Ie "controlling" Ic previously, but you never addressed my reply. In the active region of a BJT, the Ic is almost the same as Ie. The only difference is that Ic is a little smaller due to...
  13. R

    How can I simplify the denominator of the Op Amp KVL formula?

    chrisjrollin, The correct word is "deduced", not "induced". Ratch
  14. R

    leading or lagging of voltage?

    The analysis proceeds correctly even though we know that charge does not pass through any capacitors in the circuit. That is because transient current still exists in the circuit itself due to the ability of capacitors to accumulate and deplete charge for finite period of time. No pretending...
  15. R

    leading or lagging of voltage?

    It is not a topic, it is an operational description of a happening event. No, I have not seen those terms used in documentation anywhere. Matter of fact, all the documentation I have seen uses the technical slang word "charge" to describe a capacitor energizing. Usually slang is not very...
  16. R

    leading or lagging of voltage?

    Laplace, Yes, since the R and C are in series, they will have the same accumulation/depletion current existing through the resistor and to/from the capacitor. Because the cap current is C dV/dt, and the applied voltage is sinusoidal, the cap voltage will be locked into at a 90° lag with...
  17. R

    Capacitors dielectric

    AC or DC never passes through an ideal capacitor. If it does, the capacitor is defective and leaky. A perfect dielectric is a perfect insulator. A DC will accumulate a charge on one capacitor plate and deplete the charge on the opposite plate. This will enable a transient current to exist...
  18. R

    leading or lagging of voltage?

    If you switch the circuit on and off, the voltage and current waveforms will not have the same shape in relation to each other as a sinusoidal waveform will. So how can you determine where the current phase reference is if you cannot relate it to the voltage shape? A step voltage is a...
  19. R

    leading or lagging of voltage?

    Your description of phase difference is wrong. Using the transient response by a step voltage to describe phase difference is meaningless because a step voltage is not repetitive and has no phase reference. Always, the current to/from the plates of the capacitor will be I = C dV/dt . Like...
  20. R

    leading or lagging of voltage?

    Yes, the energy to move the charge and produce the current when the applied voltage is zero comes from the electrostatic field produced by grouping an excess charge on one capacitor plate and removing charges from the opposite plate. Whenever an unequal density of charges occur between two...
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