I've had a good understanding of what a capacitor does since I was a kid. It charges up to the line voltage (in the he case of a decoupling or filter cap) and when the line voltage dips, it releases some of its voltage... Now I know there is one very important mistake at the end of that sentence, but bare bear with me.
A cap does not "charge up." It contains the same amount of net charge at 10, 100, or 1000 volts as it does at zero volts. For every coulomb of charge imposed on either plate, the same amount of charge is removed from the opposite plate. This means that the net loss/gain of charge is zero. What you should understand is a cap stores energy in the form of an electrostatic field. Everyone should say a capacitor becomes
energized, not charged. A cap energized to 100 volts contains more energy that a cap energized to 10 volts (E = 1/2 C V^2).
Then I learned what an inductor does a few years ago. It stores current in a magnetic field and releases the current when the current in the circuit drops... Again, I realize the mistake (similar to the mistake I made above).
Wrong! Neither a cap or coil store either voltage or current. Both store electrical energy (electric fields or magnetic fields). Both the voltage and current involved are consequences of how fast the energy is stored and released, and what type of electrical energy (electric or magnetic) fields are involved.
Now, after really thinking about it, it hit me and I discovered where my understanding is flawed. It all revolves around Ohm's law. A capacitor doesn't release it's "voltage", that actually doesn't make sense, it actually releases current to maintain the voltage through the load. Again V=IR. Same thing goes for the inductor, it pushes a higher voltage through the load to maintain the current.
Same answer as above. Voltage is the energy density of a charge (joules/coulomb). A density (voltage) cannot be stored. It just exists. You would not say velocity can be stored, would you? Neither can density. If a voltage exists across the plates of a cap, you can be sure that energy is being stored in the cap. The voltage represents the electric field energy with respect to the amount of charge difference between the plates (joules/coulomb).
I think there's a problem when people try to explain what these passive components do to beginners in EE. It seems like people always use voltage to describe what a capacitor does and always use amperage to describe what an inductor does. Nobody really talks about how the components react with the load to give the complete picture. You just don't think about current when talking about capacitors and voltage when talking about inductors.
You have to understand how the speed those electric energy storage components accept and release energy affects the voltage and current.
So I rewrote my own understanding of each component as follows:
A capacitor tries to maintain voltage by supplying a variable amount of current to the circuit.
An inductor tries to maintain current by pushing a variable voltage through the circuit.
Wrong. The voltage and current are due to the rate of build-up and collapse of the electric and magnetic fields.
So my question is, does my new understanding make more sense? What do you guys think?
You are wrapping yourself around the axle. You had better reply to this thread with more questions and examples.
Ratch