Why Capacitors Work: Exploring Charge Storage

In summary: Imagine you have a capacitor that's been charged with electrons. When you close the gate, the electrons flow into the capacitor like water in a water tower. When you open the gate, the electrons flow out of the capacitor like water in a water tower.
  • #1
Avichal
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After studying more complicated electronics, I find myself asking this question - 'Why capacitor works?'
Why does charge get accumulated on the plates? Isn't that a higher energy state than battery?
 
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  • #2
Why does charge get accumulated on the plates?
Opposite charges attract each other, and the other side has the opposite charge.
Isn't that a higher energy state than battery?
No, the capacitor gets charged until the energy per electron is the same in both.
 
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  • #3
mfb said:
No, the capacitor gets charged until the energy per electron is the same in both.

Why is it not a higher energy state? When the circuit is closed I understand why electrons flow. But when it is open(which is in this case), I don't understand why electrons should flow.
 
  • #4
Avichal said:
Why is it not a higher energy state? When the circuit is closed I understand why electrons flow. But when it is open(which is in this case), I don't understand why electrons should flow.

The circuit is only "open" when the capacitor is fully charged. Until then current will flow into one plate and out of the other until the voltage drop across the plates is equal to the applied voltage.
 
  • #5
If you are familiar with static electricity you will know that it's possible for an object like a plastic comb or rod to become charged up (eg it acquires a surplus or shortage of electrons). Much the same thing happens with each plate of a capacitor...

Imagine one plate (lets call it the top plate) behaves like a comb that you have charged up with extra electrons. If that top plate is close to another plate (eg the bottom plate) then the electrons in the top plate will repel electrons in the bottom plate (like charges repel remember). The electrons in the bottom plate will try to move away from the top plate by escaping down the wire.

So now you have electrons on the top plate and a shortage of electrons on the bottom plate... and for awhile you had current flowing. You put electrons into the top plate and different electrons left the bottom plate.

If you have electrons on one plate and a shortage on the other then there will be an electric field/ voltage between the two plates. This voltage will build up until it's greater than the voltage that caused the surplus of electrons on the top plate. At that point no more electrons flow onto the top plate or out of the bottom plate.
 
  • #6
A capacitor is somewhat analogous to a water tower. You can pump water in, then close off the gate. Later, you can open the gate and water will flow out. Now replace water with charge, and water pressure with voltage.
 

1. How do capacitors store charge?

Capacitors store charge by using two conductive plates separated by an insulating material, also known as a dielectric. When a voltage is applied to the capacitor, one plate becomes positively charged and the other becomes negatively charged. This creates an electric field between the plates, which stores the charge in the form of potential energy.

2. What materials are commonly used as dielectrics in capacitors?

Dielectrics can be made from a variety of materials, including ceramic, plastic, paper, and electrolytic solutions. The type of dielectric used depends on the desired capacitance, voltage rating, and frequency range of the capacitor.

3. Why are capacitors used in electronic circuits?

Capacitors are used in electronic circuits for a variety of purposes, including energy storage, filtering, and timing. They are also used to reduce electronic noise and to stabilize voltage levels.

4. How does the capacitance of a capacitor affect its performance?

The capacitance of a capacitor is a measure of its ability to store charge. A higher capacitance means that the capacitor can store more charge, which can have an impact on its performance in terms of energy storage and filtering capabilities.

5. What is the role of capacitors in power supplies?

Capacitors are commonly used in power supplies to store energy and provide a stable source of voltage. They help to regulate the flow of electricity, reducing fluctuations and ensuring a steady supply of power to electronic devices.

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