# A battery, two capacitors, and a switch

• *best&sweetest*
In summary, after flipping the switch, the charge on C1 and C2 is the same. The voltage across the two capacitors must also equal.
*best&sweetest*

## Homework Statement

If the switch is flipped from position A to position B, what's the charge on capacitor C1 and C2?

Q=CV

## The Attempt at a Solution

I know that the capacitor C1 gains potential difference of 200V (= potential difference of a battery) and has charge Q = C1*200, but I'm not sure what happens once the flip is switched. My assumption is that it must discharge because it is no longer connected to the battery, but does it discharges until Q = 0 or until the charge on C2 = charge on C1. Could somebody please explain to me what exactly happens once the switch is in position B
Thank you!

Charge moves down the potential hill. (conventional)

from conservation of charge: amount of charge stored when in position A must be same as in position B, the only different is that now you have two capacitors to share the storage.. now, assuming that the second capacitor is initially uncharged, then the total charge in the two-capacitor system must be the same as before... due to how the circuit is set up the voltage across the two capacitor must also equal...

mjsd said:
from conservation of charge: amount of charge stored when in position A must be same as in position B, the only different is that now you have two capacitors to share the storage.. now, assuming that the second capacitor is initially uncharged, then the total charge in the two-capacitor system must be the same as before... due to how the circuit is set up the voltage across the two capacitor must also equal...

I got it. Thank you very much. I knew about the voltage, but I forgot to consider charge conservation. Thanks!

I'm trying to solve a similar problem and I understand everything except the following part:

Why are C1 & C2 in parallel after flipping the switch to B?

Doesn't the circuit just look like this after the switch goes to B (ignoring the part of the circuit where they connect to the battery because that is not functional now):

So aren't they really in serial?

Last edited:

## 1. What is the purpose of a battery, two capacitors, and a switch?

The battery, two capacitors, and a switch are all components of an electrical circuit. The battery provides a source of electrical energy, the capacitors store this energy, and the switch controls the flow of the energy through the circuit.

## 2. How do the capacitors function in this circuit?

The capacitors act as temporary storage units for electrical energy. When the switch is closed, the capacitors charge up with the energy from the battery. When the switch is opened, the capacitors release this stored energy back into the circuit.

## 3. What is the role of the switch in this circuit?

The switch controls the flow of electrical energy through the circuit. When the switch is open, no energy can flow through the circuit. When the switch is closed, the circuit is complete and energy can flow through it.

## 4. What happens if the capacitors are not the same size?

If the capacitors are not the same size, they will have different capacitances, meaning they can store different amounts of energy. This can affect the overall functioning of the circuit, as the energy stored in the capacitors will not be equal.

## 5. Can this circuit be used for anything practical?

Yes, this circuit can be used for a variety of practical applications, such as in electronic devices or as a component in larger circuits. It can also be used for experiments and demonstrations in physics or electrical engineering.

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