- #1
mbaban
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Please help me with this "capacitors" problem ?
Two capacitors connected in Parallel and their sum(Ceq12) is connected in series with a third capacitor .
Givens are : (( C1 = unknown value (X) , C2 = 4uF , C3 = 18 uF , Q1 = 300 uC , V = 90V ))
The question wants the value of C1 , ( I find it impossible to solve because givens aren't enough but my teacher insists that it can be done ) Please help ! {if it helps the answer is 5uF but i can figure how }.
OK here is what i did :
Equations :
-Parallel : Ceq = C1 + C2
-series : 1/Ceq = 1/c1 + 1/c2
-Q= CV , C = Q/V , V= Q/C
- in series Q=Q , v=v1+v2
- in parallel V=V , Q=Q1+Q2
those are the needed equations i think
ok here is what i did :
Ps : ( I am not just looking for a fast and easy way to do homework , i actually tried a lot )
-- i used 1/Ct = 1/ceq12 + 1/C3
1/Ct = 1/x+4 + 1/18
-continued to Qt = 18x+72/22+x * 90
-- i reached a quadratic equation in one of my tries
-- and now i reached 1620x-5100 = 0
{ tried many ways , got confused , dead ends , o please help me }
Two capacitors connected in Parallel and their sum(Ceq12) is connected in series with a third capacitor .
Givens are : (( C1 = unknown value (X) , C2 = 4uF , C3 = 18 uF , Q1 = 300 uC , V = 90V ))
The question wants the value of C1 , ( I find it impossible to solve because givens aren't enough but my teacher insists that it can be done ) Please help ! {if it helps the answer is 5uF but i can figure how }.
OK here is what i did :
Equations :
-Parallel : Ceq = C1 + C2
-series : 1/Ceq = 1/c1 + 1/c2
-Q= CV , C = Q/V , V= Q/C
- in series Q=Q , v=v1+v2
- in parallel V=V , Q=Q1+Q2
those are the needed equations i think
ok here is what i did :
Ps : ( I am not just looking for a fast and easy way to do homework , i actually tried a lot )
-- i used 1/Ct = 1/ceq12 + 1/C3
1/Ct = 1/x+4 + 1/18
-continued to Qt = 18x+72/22+x * 90
-- i reached a quadratic equation in one of my tries
-- and now i reached 1620x-5100 = 0
{ tried many ways , got confused , dead ends , o please help me }
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