Charge on capacitors, total energy

In summary, the conversation discusses the behavior of two capacitors connected in parallel. The first capacitor is charged to 10V and isolated, while the second one is uncharged. When connected, the two capacitors quickly reach the same potential difference between their plates. The question asks for the charge and total energy stored in the capacitors, and also for recommendations on websites to learn more about capacitors. The conversation also mentions the option of looking up information in books or through a Google search.
  • #1
kat_r
3
0
Can some one please help me with this question:
A 20 microfarrad capacitor is charged to 10V and isolated. A second uncharged 20 microfarrad capacitor is now connected to the plates of the other. The capacitors rapidly come to the same pd between their plates. What is the charge on each capacitor now? What is the total energy stored in the two capacitors? Comment on your answer. Now repeat with the second capacitor rated at 30 microfarrads.

While we're on the subject of capacitors does anyone know any good websites about capacitors?
 
Physics news on Phys.org
  • #2
Maybe:
http://scienceworld.wolfram.com
Or if you're looking for specifics about Capacitors I could always look it up in the books I got... or you could Google. :)
 
  • #3


Once the capacitors are connected, the charge on each capacitor will be the same, as they are in parallel. This means that the charge on each capacitor will be 10 microcoulombs (since Q = CV, where Q is charge, C is capacitance, and V is voltage).

The total energy stored in the two capacitors can be calculated by using the formula for energy stored in a capacitor: E = 1/2 * CV^2. Plugging in the values, we get a total energy of 1 millijoule (0.5 * 20 x 10^-6 F * 10^2 V).

If we repeat the scenario with the second capacitor rated at 30 microfarads, the charge on each capacitor will still be 10 microcoulombs, but the total energy stored will now be 1.5 millijoules (0.5 * 30 x 10^-6 F * 10^2 V). This shows that the energy stored in a capacitor is directly proportional to its capacitance.

As for good websites about capacitors, some reliable sources include All About Circuits, Electronics Tutorials, and SparkFun. These websites provide comprehensive information about capacitors, including their types, uses, and calculations.
 

What is the equation for calculating the charge on a capacitor?

The equation for calculating the charge on a capacitor is Q = CV, where Q is the charge in coulombs, C is the capacitance in farads, and V is the voltage across the capacitor in volts.

How does the charge on a capacitor affect its energy storage?

The charge on a capacitor directly affects its energy storage. The more charge that is stored on the capacitor, the more energy it can hold. This is because the energy stored in a capacitor is proportional to the square of the charge on it.

Can the charge on a capacitor be negative?

Yes, the charge on a capacitor can be negative. This occurs when the polarity of the capacitor is reversed, with the negative terminal connected to the positive side and vice versa.

How does changing the capacitance affect the charge on a capacitor?

Changing the capacitance of a capacitor will also change the charge it can hold. If the capacitance is increased, the charge that can be stored will also increase, and vice versa. This is because of the direct relationship between capacitance and charge.

What is the relationship between the charge on a capacitor and the voltage across it?

The charge on a capacitor is directly proportional to the voltage across it. This means that if the voltage is doubled, the charge will also double. Similarly, if the voltage is halved, the charge will also be halved.

Similar threads

  • Introductory Physics Homework Help
Replies
5
Views
907
  • Introductory Physics Homework Help
Replies
4
Views
2K
  • Introductory Physics Homework Help
Replies
3
Views
2K
  • Introductory Physics Homework Help
Replies
1
Views
727
  • Introductory Physics Homework Help
Replies
12
Views
4K
  • Introductory Physics Homework Help
Replies
28
Views
2K
  • Introductory Physics Homework Help
Replies
3
Views
3K
  • Introductory Physics Homework Help
Replies
1
Views
701
  • Introductory Physics Homework Help
Replies
11
Views
2K
  • Introductory Physics Homework Help
Replies
5
Views
931
Back
Top