Physics Basics: Capacitor Charging & Discharging

[katchakern200]

Here is the question that I'm given:

Consider a circuit with a capacitor, battery, wire, and bulb. Describe the source(s) of charge during:

1. capacitor charging
2. capacitor discharging

What is the cause of charge motion during capacitor charging?

Using the analogy of the air capacitor, what do you think might be the cause of charge motion during capacitor discharging?

My solution: I thought that the battery in a circuit provided the energy for the charge to move through, but would this be a correct answer to the first question? Wouldn't the charge come from the discharged capacitor when the capacitor is discharged? For the second question, "What is the cause of charge of motion during capacitor charging?" I have no idea what to write. I don't even get what the question is asking. For the last question, I don't understand it either. I just need some help in understanding all of this!

The Attempt at a Solution

 

[Nick89]

Think of the capacitor as two sheets of metal, separated by a bit of air.
If the capacitor is charged, then one sheet will hold positive charges (or lack of negative charges) and the other sheet will hold negative charges. What do you know about when these two types of charges meet? They attract each other! But since the charges cannot go through the air, they have to go through the rest of the circuit.
If the capacitor is being charged then something must 'push' the charges back into the sheets so they don't flow back to each other (through the circuit). The battery is ofcourse what supplies the energy to do this.

Now consider what happens when the battery is switched off. What are the charges going to do? So what is the source of energy to discharge the capacitor?

 

[Moetasim]

:

I am happy to help you understand the concept of capacitor charging and discharging. Let's start with the first question:

1. During capacitor charging, the source of charge is the battery. When a battery is connected to a circuit with a capacitor, it creates a potential difference or voltage across the capacitor. This potential difference causes electrons to move from the negative terminal of the battery to the positive terminal, creating a flow of charge through the circuit. This charge accumulates on the plates of the capacitor, causing it to become charged.

2. During capacitor discharging, the source of charge is the stored charge on the capacitor itself. When the circuit is closed and the capacitor is connected to a load (such as a bulb), the stored charge on the capacitor flows through the circuit, causing the bulb to light up. This is known as capacitor discharging.

Now, for the question about the cause of charge motion during capacitor charging. The cause of charge motion is the potential difference created by the battery. This potential difference creates an electric field which exerts a force on the electrons, causing them to move through the circuit and onto the plates of the capacitor.

As for the analogy of the air capacitor, it may help to think of the air as the dielectric material between the plates of the capacitor. When the capacitor is being charged, the air molecules are being polarized and aligning with the electric field, causing a buildup of charge on the plates. During discharging, the air molecules return to their normal state, causing the stored charge to flow through the circuit.

I hope this helps to clarify the concept of capacitor charging and discharging. If you have any further questions, please don't hesitate to ask. Remember, as a scientist, it's important to always ask questions and seek understanding. Good luck with your studies!