# The total equivalent capacitance

• Samanko
In summary, the circuit shown has two separate instances of two capacitors in parallel, those with the voltmeter connected in parallel with them on the left, and those parallel to each other on the right. The total potential difference is 2V. The total equivalent capacitance is C.
Samanko
Moved from a technical forum, so homework template missing.

The circuit is shown.
The explanation says
"The total potential difference is 2V."
"The total equivalent capacitance is C."

Since there are 4 parallel capacitors, isn't the equivalent capacitance 4C and total potential difference 4V?

For capacitors to add they must all be in parallel with each other.

The circuit shown has two separate instances of two capacitors in parallel, those with the voltmeter connected in parallel with them on the left, and those parallel to each other on the right.

The instance on the left does indeed have an equivalent value of 2C, and so does the instance on the right.

The two instances are however in series with each other.

Do you know how to find the value of capacitors in series? If not, look it up. That should give you enough information to find the equivalent capacitance of the circuit.

Cheers,
Tom

Samanko and Delta2
Tom.G said:
For capacitors to add they must all be in parallel with each other.

The circuit shown has two separate instances of two capacitors in parallel, those with the voltmeter connected in parallel with them on the left, and those parallel to each other on the right.

The instance on the left does indeed have an equivalent value of 2C, and so does the instance on the right.

The two instances are however in series with each other.

Do you know how to find the value of capacitors in series? If not, look it up. That should give you enough information to find the equivalent capacitance of the circuit.

Cheers,
Tom

I understand each of two capacitors of two instances are parallel. But I don't understand how come the two instances are in series. The wire is directly connected to each instance. Isn' it in parallel?

Samanko said:
I don't understand how come the two instances are in series. The wire is directly connected to each instance. Isn' it in parallel?
How should two instances in series look like according to you?

Samanko
A.T. said:
How should two instances in series look like according to you?

I thought the capacitors should be connected by one wire to be in series.

Samanko said:
I thought the capacitors should be connected by one wire to be in series.
Illustrating what @Tom.G said:

The pair of capacitors circled in green are in parallel. This pair can be replaced by an "equivalent" single capacitor with a capacitance value of 2C.

Similarly: The pair of capacitors circled in red are in parallel. This pair can also be replaced by an "equivalent" single capacitor with a capacitance value which is also 2C.

Redraw the circuit.

Do you agree that these resulting capacitors are in series?

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Delta2 and Tom.G
Samanko said:
View attachment 250421

I thought the capacitors should be connected by one wire to be in series.
That's all 4 capacitors in series. I asked you how the 2 instances (each consisting of 2 parallel capacitors) would look in series, if you don't think that's what your circuit is.

Samanko
A.T. said:
That's all 4 capacitors in series. I asked you how the 2 instances (each consisting of 2 parallel capacitors) would look in series, if you don't think that's what your circuit is.
Thank you!

## 1. What is capacitance and how is it calculated?

Capacitance is the ability of a system to store electrical charge. It is calculated by dividing the amount of charge stored by the potential difference across the system (C = Q/V).

## 2. What is the total equivalent capacitance and how is it different from individual capacitances?

The total equivalent capacitance refers to the combined capacitance of a system with multiple capacitors connected in series or parallel. It is different from individual capacitances because it takes into account the overall effect of all the capacitors in the system, rather than just one.

## 3. How is the total equivalent capacitance calculated for capacitors in series?

For capacitors in series, the total equivalent capacitance is calculated by adding the reciprocals of the individual capacitances and then taking the reciprocal of the sum (1/Ceq = 1/C1 + 1/C2 + ... + 1/Cn).

## 4. How is the total equivalent capacitance calculated for capacitors in parallel?

For capacitors in parallel, the total equivalent capacitance is calculated by adding the individual capacitances (Ceq = C1 + C2 + ... + Cn).

## 5. How does the total equivalent capacitance affect the overall capacitance of a circuit?

The total equivalent capacitance affects the overall capacitance of a circuit by determining the amount of charge that can be stored and the potential difference across the system. A higher total equivalent capacitance will result in a larger overall capacitance and vice versa.

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