Charged capacitor connected to an uncharged capacitor

In summary, a charged capacitor connected to an uncharged capacitor is a circuit where the two capacitors are connected and the charged capacitor transfers some of its stored energy to the uncharged capacitor. The resulting charge on the two capacitors is equal to the sum of their individual charges before being connected, and the voltage across both capacitors is equalized. The capacitance of the capacitors affects the transfer of energy by determining how much charge can be stored in each capacitor.
  • #1
Bolter
262
31
Homework Statement
Find the pd across the combined capacitors
Relevant Equations
Q = CV
Hi there, tried doing this question but not sure if what I did for part b is right?

Screenshot 2020-05-12 at 22.51.17.png


IMG_4908.jpg


Appreciate any help! Thanks
 
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  • #2
Yes. Fine.

As it's so simple (the numbers), you might like to do an intuitive check and say something like,
The 4 μF is double the 2 μF, so its like you end up with 3 caps of 2 μF in parallel sharing the same charge.
So each cap has 1/3 of the total charge and so must be charged to 1/3 of the voltage that the single 2 μF needed.
 
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Related to Charged capacitor connected to an uncharged capacitor

What is a charged capacitor connected to an uncharged capacitor?

A charged capacitor connected to an uncharged capacitor is a circuit arrangement where two capacitors are connected together in a series or parallel configuration. One capacitor has been previously charged with electric charge, while the other capacitor has no charge.

What happens when a charged capacitor is connected to an uncharged capacitor?

When a charged capacitor is connected to an uncharged capacitor, the electric charge from the charged capacitor will flow into the uncharged capacitor until both capacitors have the same voltage. This process is known as charge sharing.

What is the final voltage of the charged and uncharged capacitors after they are connected?

The final voltage of the charged and uncharged capacitors will be the same, as charge sharing will occur until both capacitors have equal voltage. This voltage will be determined by the capacitance values of the two capacitors and the initial charge on the charged capacitor.

Can a charged capacitor connected to an uncharged capacitor store more energy than a single charged capacitor?

No, the total energy stored in the two capacitors after they are connected will be the same as the energy stored in the single charged capacitor before they were connected. However, the energy will be distributed between the two capacitors based on their capacitance values.

What is the time constant for a charged capacitor connected to an uncharged capacitor?

The time constant for a charged capacitor connected to an uncharged capacitor is the time it takes for the voltage on the capacitors to reach 63.2% of the final voltage during charge sharing. It is calculated by multiplying the capacitance of the two capacitors in the circuit.

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