capacitancechargeelectric-circuits
When capacitors are connected in series, similar but opposite charges appear on every adjacent plate. How and why this happens ? Suppose charge appeared on plate A is $Q$ and then charge on plate F will be $-Q$ , as of now everything is ok but now they say charge on plate B will also be $-Q$ and so on. How can one confirm this?! The plates B and C are isolated, how such a symmetric condition is obtained. Please explain the core working.
Your charge distribution is correct, though I usually don't focus on using a "correct" $\pm$ distribution in capacitors--if your sign is incorrect, you get a negative value of charge on the + plate. No biggie. In complex situations, it is sometimes even impossible to predict cjarge distribution without solving the circuit.
And your book is incorrect. $C_1-C_2$ are in series, though the entire branch is in parallel with $C_3$ and its opposite branch.
Parallel is when the current is split, while series is when current is constant. Series is a single wire with an in and an out, with components along the wire. Parallel is when there are many wires with their ends twisted together. Current goes in/out through the twisted ends.
You seem to have grasped that, though :)
Out of curiosity, which book is this? (the capacitors look like they're from Resnick)
then why is there no potential difference between the two capacitors
It's not quite clear what you mean here but do understand that charged capacitors are electrically neutral.
When a capacitor is "charged", it is not electrically charged, it is energy charged in the same sense as when we say a battery is charged.
There is nothing mysterious about two series connected circuit elements having different voltage drops. Think of two series connected resistors with different resistor values.
I would have thought that as plate B is positively charged and plate C is negatively charged, there would be a potential difference between the two
You're forgetting something fundamental: The plates B and C along with the wire that connects them are conductors. But, for an ideal conductor, charge distributes itself so that there is no (static) potential difference across the conductor.
The voltage between the bottom plate of C1 and the top plate of C2 is zero precisely because a conductor connects the two plates.
Best Answer
For series connected capacitors, the charging current flowing through the capacitors is the same for all capacitors as there is only one path to follow. Since capacitors in series all have the same current flowing through them, each capacitor will store the same amount of electrical charge, Q, on its plates regardless of its capacitance. This is due to the fact that the charge stored by a plate of any one capacitor must have come from the plate of its adjacent capacitor, as discussed in 1-3 below.
Again, it is due to the fact that the charge stored by a plate of any one capacitor must have come from the plate of its adjacent capacitor. Consider the following sequence, beginning at the positive terminal of the battery.
Initially, before they are connected to a voltage source (e.g., battery) the capacitors are uncharged, and if the plates are made of metal, then each plate has free (mobile) electrons on it and an equal amount of immobile protons so that the plates are electrically neutral. See Figure 1.
Now a battery is connected to the series capacitors. See Fig 2. The positive terminal of the battery pulls electrons from plate A, leaving the plate positively charged. At the same time, the negative terminal of the battery supplies the same number of electrons (because the current is the same) to plate F neutralizing neutralizing protons on the plate making it negatively charged. At this instant, plates B, C, D and E still have mobile electrons on them as as shown in Fig 1, but not shown in Fig 2.
Now refer to Fig 3. The positively charged plate A will now attract (pull) the free electrons shown in Fig 1 from plate C over to plate B due to the closer proximity of B to A making plate B negatively charged and plate C equally positively charged.
Finally, again referring to Fig 3, the positively charged plate C will attract (pull) free electrons from plate E over to plate D making plate D negatively charged and plate E positively charged by the same amount.
Note that above can be viewed starting with the negative terminal of the battery, in which case the shifting of electrons is due to the repulsive electron force at plate F.
Plages B and C (as well as D and E) are not isolated because they are subjected to the electric fields of other plates as described in 1 through 3 above.
Hope this helps.