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Question

Three capacitors (4.0, 6.0, and 8.0 µF) are connected in series across a 50.0-V battery. Find the voltage across the 4.0-µF capacitor.
V

A 3.0 µF capacitor and a 4.0 µF capacitor are connected in series across a 46.0 V battery. A 15.0 µF capacitor is also connected directly across the battery terminals. Find the total charge that the battery delivers to the capacitors.
C

Answer 1

Assuming that the stady state is acheived the voltage will be divided proportionally between the capacitores.

a) Qt= V C

Using voltage divider
V(4uF)=[Vt/(C total)] C (4 uF) Note C total is not C equivalent for a series circuit!)
We have

V(4uF)=(50/(4+ 6 +8))4=100/9 volts

b) again Qt=V C

In this case Qt=Q1+Q2
Q1=V (C equiv)
Q2=V (C 15 uF)

Qt=46 ((12)/(3+4))e-6 + 15e-6 )=
Qt=46v (16.7e-6uf)= 7.689 e-4 Coulombs