Three initially uncharged capacitors are arranged with batteries as shown in. Find the charge on each capacitor.
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Explanation

Let potential at `1` is `0`, so at `4` it is `30 V`, at `6` it is `10 V`, and at point `7` potential is `-25 V`. Let us assume potential at point 5 be `xV`, Let us take isolated system as shown in the figure. (Total charge of all the plates cannected to`5` must be same as before, i.e., `0`.)
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`:. 1(x-10)+2(x-30)+2(x+25)=0`
or `5x=20`or `x=4`
Final charges:
On `C_(1),Q_(1)` is `(30-4)2=52 muC`
On `C_(2),Q_(2)` is`2(4-(-25))=58 muC`
On `C_(3),Q_(3)` is `1(10-4)=6 muC`.