الفيزياء العامة الجزء الثاني#موقع الفيزياء.كوم

Capacitors and capacitance
Example 6.4
In the above example 6.3 determine the potential difference across each
capacitor and the charge on each capacitor if the total charge on all the
six capacitors is 384µC.
Solution
First consider the equivalent capacitor C eq to find the potential between
points a and b (V ab )
V
Q =
C
384 = =
ab
ab
48
ab
8
V
Second notice that the potential V kl =V ab since the two capacitors between k
and l are in parallel, the potential across the capacitors C 1 and C 5 = 48V.
V 1 =48V and Q 1 =C 1 V 1 =48µC
And for C5
V 5 =48V and Q 5 =C 5 V 5 =240µC
For the circuit (iv) notice that V mh =V ab =48V, and
Q mh =C mh V mh =2×28=96µC
Since the two capacitors shown in the circuit (iii) between points m and h
are in series, each will have the same charge as that of the equivalent
capacitor, i.e.
Q mh =Q gh =Q mh =96µC
V
V
Q =
C
96 =
mg
mg = 24
mg
4
Q =
C
96 =
gh
gh = 24
gh
4
Therefore for C 4 , V 4 =24 and Q 4 =96µC
V
V
In the circuit (ii) the two capacitor between points g and h are in parallel so
the potential difference across each is 24V.
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