A 9.0 μF and 4.0 μF capacitors are connected in parallel

In summary, the net capacitance of a 9.0 μF and 4.0 μF capacitors connected in parallel and in series with a 12.0 μF capacitor is 6.24 micro F. When 32 V is applied across the network, the voltage across the 12.0 μF capacitor is 16.64 V, the voltage across the 13.0 μF capacitor is 15.36 V, and the voltage across the 9.0 μF and 4.0 μF capacitors is 15.36 V.
  • #1
mikebc
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A 9.0 μF and 4.0 μF capacitors are connected in parallel...

Hi, I understand how to do most of this question, I completed "A", but I am confused with question "B". I think that the series capacitor would have full voltage going across it and that the parallel capacitors would have less voltage. But since resistors work oppositely then capacitors and this is the same way to work out resistor voltage I am wondering if I am working it out wrong. Any help would be appreciated.

Question
A 9.0 μF and 4.0 μF capacitors are connected in parallel, and this combination is
connected in series with a 12.0 μF capacitor.
a. What is the net capacitance?
b. If 32 V is applied across the whole network, calculate the voltage
across each capacitor.


I have attached a scan of how I think that it works.

Thanks!
 
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  • #2
Oops, I forgot to add attachment...

Here is the scan.
 

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  • #3
Equivalent capacitance = 6.24 micro F. From Q = CV we get charge Q drawn from the battery = 6.24 x 10^-6 x 32 = 199.68 X 10^-6 C.

When capacitors are in series, the charge on each capacitor is same. 13 micro F capacitor and 12 micro F cap are in series. Hence, Q the charge on each of these is same (199.68 X 10^-6 C).

V = Q/C. Hence voltage across 12 micro F cap = 199.68 X 10^-6/12 x 10^-6 = 16.64 V

Voltage across 13 micro F cap = 199.68 X 10^-6/13 x 10^-6 = 15.36 V

As the voltage across capacitors in parallel is same, voltage across each of 9 & 4 micro F caps will be 15.36 V.
 
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  • #4
Thank you for explaining that so clearly for me. Some concepts my textbook does not clearly explain, or it is just expected to be understood. Cheers!
 

What is the total capacitance when a 9.0 μF and 4.0 μF capacitors are connected in parallel?

The total capacitance when capacitors are connected in parallel is equal to the sum of their individual capacitances. In this case, the total capacitance would be 13.0 μF.

How does the voltage affect the capacitance when capacitors are connected in parallel?

The voltage across each capacitor remains the same when they are connected in parallel. Therefore, the voltage does not affect the capacitance in this case.

What is the equivalent capacitance when more than two capacitors are connected in parallel?

The equivalent capacitance for a group of capacitors connected in parallel is equal to the sum of the individual capacitances. This means that if there are more than two capacitors, you simply add up all of their capacitances to get the equivalent capacitance.

Can capacitors with different capacitances be connected in parallel?

Yes, capacitors with different capacitances can be connected in parallel. The equivalent capacitance will be the sum of the individual capacitances, regardless of their values.

What happens to the total charge when capacitors are connected in parallel?

The total charge is divided between the capacitors when they are connected in parallel. The sum of the individual charges on each capacitor will be equal to the total charge.

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