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go2255
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Homework Statement
A 3nF Capacitor is parallel with a 4nF Capacitor.
And they are connected with a 5nF Capacitor in series.
IF the external voltage supply is 20V.
FIND (a)the p.d across each capacitor,
and (b)the total charge in the three Capacitor.
The Attempt at a Solution
(a)
p.d across the 3nF,4nF capacitor=20x(5/(7+5))
=8.33V
p.d across the 5nF capacitor=20-8.33
=11.67V
(b)I try it in two method,but they have different answers.I don't know why!
Method 1:
equivalent Capacitor=2.917nF
C=Q/V
2.917nF=Q/20
Q=58nC
Method 2:
charge in 3nF Capacitor=3n x8.33
=25nC
charge in 4nF Capacitor=4n x8.33
=33.3nC
charge in 5nF Capacitor=5n x11.67
=58nC
tatol charge:25+33.3+58
=116.3nC