Capacitors reconnected (finding charge and potential)

In summary, the conversation is discussing a figure with two separate conductors labeled as Q1 and Q2. The top piece has +Q on the left side and -Q on the right, while the bottom piece has the same thing reversed. The net charge on each conductor appears to be 0, but in figure (c) the top piece has a net positive charge and the bottom piece has a net negative charge. The explanation is that the charges Q1 and Q2 are of different sizes and do not completely cancel, leaving a remaining uncancelled charge q.
  • #1
luigidorf
15
0

Homework Statement


L4hGJ.jpg


Homework Equations


Q = CV

The Attempt at a Solution


It's already solved for me; I just don't understand it.

In figure (b) it looks like there are two separate conductors: one on top, and one on the bottom. The top piece has +Q on the left side and -Q on the right, and the bottom piece has the same thing except reversed. Seems to me that this would make the net charge on each conductor 0... But somehow they get to figure (c) where the top piece has a net positive charge and the bottom piece has a net negative charge. What am I missing?
 
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  • #2
luigidorf said:
In figure (b) it looks like there are two separate conductors: one on top, and one on the bottom. The top piece has +Q on the left side and -Q on the right, and the bottom piece has the same thing except reversed. Seems to me that this would make the net charge on each conductor 0... But somehow they get to figure (c) where the top piece has a net positive charge and the bottom piece has a net negative charge. What am I missing?

The charges Q1 and Q2 are of different sizes. They don't completely cancel. They leave charge q remaining uncancelled.
 
  • #3
Ah there it is. Thanks!
 

Related to Capacitors reconnected (finding charge and potential)

1. How do I find the charge on a capacitor after it has been reconnected?

The charge on a capacitor can be found by using the formula Q=CV, where Q is the charge, C is the capacitance of the capacitor, and V is the potential difference across the capacitor. Make sure to use the correct units for capacitance (Farads) and potential difference (Volts).

2. What is the potential difference across a capacitor after it has been reconnected?

The potential difference across a capacitor can be found by using the formula V=Q/C, where V is the potential difference, Q is the charge on the capacitor, and C is the capacitance of the capacitor. Make sure to use the correct units for charge (Coulombs) and capacitance (Farads).

3. Can I use the same formula to find the charge and potential difference for capacitors in series and parallel?

Yes, the same formulas can be used for capacitors in series and parallel, but the values for capacitance and potential difference may vary depending on the circuit configuration. For capacitors in series, the total capacitance is equal to the inverse of the sum of the inverses of each capacitor's individual capacitance. For capacitors in parallel, the total capacitance is equal to the sum of each capacitor's individual capacitance.

4. How does the charge and potential difference change when capacitors are added in series or parallel?

In a series circuit, the total charge remains the same, but the potential difference is divided among the capacitors. In a parallel circuit, the potential difference remains the same, but the total charge is divided among the capacitors. Adding more capacitors in series or parallel will increase the total capacitance and affect the charge and potential difference accordingly.

5. What happens to the charge and potential difference when a capacitor is disconnected from a circuit?

When a capacitor is disconnected from a circuit, the charge on the capacitor remains the same, but the potential difference across the capacitor becomes zero. This is because the capacitor is no longer connected to a circuit and cannot maintain its charge.

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