The discussion revolves around determining the charge on the plates of a parallel plate capacitor given the area and separation between the plates. Participants explore the relationship between capacitance, voltage, and charge in the context of electrostatics.
The discussion is ongoing with various interpretations being explored. Some participants have provided guidance on the relationships between charge, voltage, and capacitance, while others are questioning the assumptions made about charge distribution and grounding.
There are discussions about the implications of grounding on charge distribution, the assumptions regarding voltage references, and the potential for different charge distributions on the plates based on their connections in the circuit.
##C##=##\frac{aε0}{d}##gneill said:
No. That has two capacitance terms. You need a voltage and a capacitance: Q = CV.gracy said:
Still too hasty. You've written the same thing againgracy said:
But hint says plate B would have different charge.gneill said:
Yes. I presume "plate B" is the middle plate of the physical setup? You didn't label your diagram.gracy said:
gneill said:
gneill said:
No, "earth" is a vast pool of available charges, both positive and negative and overall neutral. It can supply whatever charge is required to respond to electrostatic forces. Or, if you like, it can source or sink any amount of electrons, if you want to go with an atomic model for the plates and conductors.gracy said:
I did not understand that.gneill said:
V is taken to be a voltage supply. Voltage is a potential difference. When a terminal is just labeled "V" then it is assumed that that potential difference is between the terminal and the ground reference.gracy said:
I don't quite get the relationship between being symmetrical and connected to the same potential and having same charge distribution.gneill said:
gracy said:
That is for one capacitor(1-2 or 3-4). The capacitors are in parallel. So you can find the total charge now.gracy said:
If you rotate the drawing on the page, do you expect the charges on the plates to change? Is there any distinction (electrically) between the two outer plates?gracy said:
You'll have to explain how you ended up with different distributions on the two outer plates.
gracy said:
Its 'grounded' i.e it is at 0 potential. It doesn't have to be an actual earthing. It can be battery's -ve terminal.gracy said:
Now you've shown all the plates neutral. There should be net charge on each plate.gracy said:
As in here V is potential difference between A and Bgneill said:
Just because question says find the" charge".If this question appeared as MCQ and option was to be zero then?cnh1995 said:
I did not understand.cnh1995 said:
No. Charges will be "pushed onto" the outer plates by the voltage supply, and "pushed off" the middle plate via the ground connection. The plates will not remain neutral since charge can enter or leave via their external connections. In other words, there's no reason to balance the charges on the faces of any given plate so that they will sum to zero.gracy said:
You yourself correctly interpreted the circuit as two capacitors in parallel connected across some voltage V. So the plates MUST have a net charge.gracy said:
Right. Here's an alternative depiction of your circuit:gracy said:
The symbol used is normally called 'ground' i.e. a reference point in the circuit. Normally, it is the negative terminal of the battery (exceptions do exist), however, you can choose any point in the circuit as reference. All the voltages are measured w.r.t. that point. Earthing is done from protection point of view. Anyways, this is not the point of the discussion, so I won't say much.gracy said: