The total equivalent capacitance

[Samanko]

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?

 

[Tom.G]

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]

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

Thank you for answering.

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?

 

[A.T.]

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]

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.

 

[SammyS]

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?

 

[A.T.]

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]

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!