A
multi-plate capacitor consists of multiple charge holding plates of conductive
materials, separated by a dielectric. The dielectric prevents the plates from
shorting out each other. Leads are connected from the outer most plates to a
voltage source allowing charging and discharging of the capacitor. A typical
electrolytic capacitor achieves a multi-plate effect by rolling two plates into
a cylinder.
multi-plate capacitor consists of multiple charge holding plates of conductive
materials, separated by a dielectric. The dielectric prevents the plates from
shorting out each other. Leads are connected from the outer most plates to a
voltage source allowing charging and discharging of the capacitor. A typical
electrolytic capacitor achieves a multi-plate effect by rolling two plates into
a cylinder.
Connecting Capacitors in Parallel
Figure
1 above shows two capacitors C1 and C2 connected in
parallel across a voltage source of V. From the figure, it is noted that the
capacitors connected in parallel is like increasing the area of the plates of a
single capacitor. There the total capacitance is greater than that of either
one since both capacitors have to change from the same voltage source, the
charge draw from the voltage source (battery) is
1 above shows two capacitors C1 and C2 connected in
parallel across a voltage source of V. From the figure, it is noted that the
capacitors connected in parallel is like increasing the area of the plates of a
single capacitor. There the total capacitance is greater than that of either
one since both capacitors have to change from the same voltage source, the
charge draw from the voltage source (battery) is
QT
= Q1 + Q2
= Q1 + Q2
But
Q = CV
Q = CV
Therefore,
CTVT = C1V1 + C2V2
CTVT = C1V1 + C2V2
Since
figure is a simple parallel circuit
figure is a simple parallel circuit
VT
= V1 = V2
= V1 = V2
Therefore
VT, V1 and V2 can be replaced by V
VT, V1 and V2 can be replaced by V
CTV
= V (C1 + C2)
= V (C1 + C2)
CT
= C1 + C2
= C1 + C2
So
in general term, when a given number of capacitors are connected in parallel,
the total capacitance is the sum of all the individual capacitance
in general term, when a given number of capacitors are connected in parallel,
the total capacitance is the sum of all the individual capacitance
CT
= C1 + C2 + C3 +…
= C1 + C2 + C3 +…
Example
1
1
Two
capacitors C1 and C2 of capacitance 0.01µF and 0.05µF
respectively are connected in parallel in a circuit. What is the capacitance of
a single capacitor that can be used to replace C1 and C2
capacitors C1 and C2 of capacitance 0.01µF and 0.05µF
respectively are connected in parallel in a circuit. What is the capacitance of
a single capacitor that can be used to replace C1 and C2
Solution
CT
= C1 + C2
= C1 + C2
= 0.01 + 0.05 = 0.06µF
