I’ve tried to figure this one out, and honestly, there are a lot of good articles and videos out there trying to simplify and explain how certain electronic components work but they *still* get too technical and jargon-y. Like, what’s the actual for capacitors?
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They store electrical energy. The energy is stored by pumping electrons onto one side of the capacitor, and pumping them out of the other side. As you fill up one side, the electrons start repelling each other so you have to keep pushing harder and harder. That pushing takes energy and it gets stored in the capacitor like you are energy store by squeezing a spring.
The electrons really want to get back to an even distribution. They can’t go through the capacitor because there is a barrier in the way. So if they get a chance, they will try to go back through your circuit, like a spring re expanding if you give it a chance by letting go. As the electrons try to go back to an even distribution they will release energy as they go.
Capacitors store a little bit of electric charge.
The key concept that makes capacitors useful in circuits is the *rate over time* at which capacitors store and release this charge can be controlled with resistance (using resistors).
This gives control over the rate at which the flow of electricity changes.
For instance, some audio circuits are susceptible to noise, near-instantaneous fluctuations in voltage that sound like hissing in your speakers. Tapping the connection with a resistor and capacitor that lead to ground absorbs the voltage fluctuations and smooths out the remaining signal, eliminating the noise.
Because capacitors store charge over time, when combined with a transistor, they can control timing. A transistor controls flow of a large current based on the voltage at its gate. Using a capacitor, you can control how long it takes for a voltage to reach the transistor’s gate threshold (voltage at which current begins flowing through the transistor) which can be used to make the transistor create regular pulses of current.
Even more useful is when you add an inductor to a circuit with a resistor and a capacitor. An inductor gives electricity inertia, which keeps current flowing in a particular direction for a short period of time. When you combine an inductor and a capacitor, current flow in one direction is sustained by the inductor, decreasing as the capacitor charges and pushes back against the incoming electricity. When the capacitor is full, current flow stops, then reverses back through the inductor in the other direction. If the outgoing current is led back to the other side of the capacitor, the circuit oscillates as the current flows back and forth between each side of the capacitor. This creates alternating current, which is essential in many applications such as radio and audio circuits.
In short, capacitors allow the engineer to precisely control a circuit’s dynamic behaviour. When combined with transistors, they enable pulsing behaviour. When combined with inductors, they enable oscillatory behaviour.
They are a rubber band for you to store energy. Give it a Voltage (Electromotive FORCE) and it pushes back. That’s the energy you’ve stored. Give it a way to release it (by connecting it to a circuit) and you could release the energy stored.
How far the rubber band moves away from the center is the charge stored, and capacitance (Charge per Volt) tells you how elastic the rubber band is, and how much energy it could store.
Have you ever been to a water park with a big bucket that fills and then tips when it gets full? That’s what a capacitor does, but with electricity instead of water.
Capacitors are like super fast batteries. They can absorb power and release that power very fast. With the caveat they can’t contain much of it.
What are they used for does vary a lot.
If you have a signal going up and down: You use a capacitor that is just fast enough to charge with the peak of the wave and release when the bottom of the wave passes. The result is to flatten the wave. If the wave is just a power supply, you can use it to smoothen that power signal, killing dangerous peaks and filling voids. This is pretty basic. You can use it to smooth the power output of a transformer.
You can use it on a radio wave to “kill” noise on the signal. You can use a variable capacitor to tune the radio to a frequency by removing everything else. Basically, by adjusting the diode you adjust the frequency of the system.
Capacitors are pretty simple. The problem is that they can be used for a lot of tricks, and the equations to do that become quite complex quite quick.
Then there are more complex uses.
Capacitors store electric charge. As the charges accumulate in a capacitor, the voltage across it’s contacts increases. the more charges, the higher the voltage. When the contacts are connected together, the electrons leave the capacitor, an electric current briefly flows (as the charges moves) and the voltage quickly returns to zero.
ELI5: It’s a really fast battery. It doesn’t store nearly as much energy as a battery, but can be charged and discharged almost instantly.
ELI7:
If a wire is a water hose, a very accurate analogy is a container with one hose at each end, and a rubber membrane in the middle.
It’ll block a flow, but it will let *some* through for a short while, as the membrane expands in one direction like a balloon. Once fully expanded, flow will stop. It is charged.
If you were to turn off the water tap at this point, the capacitor would keep the water pressure high. It would use the expanded membrane’s energy to return water if needed, like a balloon.
If you were to pull and push water back and forth through the hose, you’d find that the capacitor isn’t much of an obstacle at all, and water would flow freely if the capacitor is big enough.
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