my lesson about capacitors and it describe the capacitors in terms of series and parallel and so on.

1. Video
Capacitors
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2. Definition of capacitors
A capacitor is a device for storing electric
charge.
Capacitance equation
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V
Q
C 

3. 20/12/2014 Capacitors 3
 Example
A 10 F capacitor has 10 V across it. What quantity of
charge is stored in it?
μC100
1010 6





CVQ
V
Q
C

4. Construction
Basically, capacitors consists of two metal
plates separated by an insulator. The
insulator is called dielectric. (e.g.
polystyrene, oil or air)
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5. Parallel plate capacitor
Absolute permittivity 0 =
Relative permittivity r
Area A
Distance between its plates d
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d
A
d
A
C r
 0
(F/m)1085.8 12


6. 20/12/2014 Capacitors 6
= Ɛ 𝑟

7. Example
A parallel plate capacitor consists of two
metal plates, each of area A=150 cm ,
separated by a vacuum gap d=0.60 cm
thick. What is the capacitance of this device
c=
Ɛ0Ɛ 𝑟 𝐴
𝑑
=
(8.85×10−12)(150×10−2)
(0.60×10−2)
= 2.213 × 10−9
= 2.213nf
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8. Types of capacitors
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Mica Ceramic Plastic film
Electrolytic Polyester Variable

9. Uses of capacitors
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Heart defibrillators Camera flash units radio receivers
to eliminate sparking
in automobile ignition
systems
filters in power
supplies

10. Charging and discharging capacitors
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63 %
37 %

11. 20/12/2014 Capacitors 11
V
Experiment

12. Time constant
The time constant is used to measure how
long it takes to charge a capacitor through a
resistor.
Energy
The energy stored in capacitor will given by
this equation
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 = CR

13. Partner Work
Question 1
Calculate the time constant.
T = R × C
= (47Ω) (1000 F)
= 47000 s
Question 2
Calculate the energy stored in a
10 F capacitor when it is charged
to 100 V.
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J0005010010
2
1
2
1 22  CVW

14. Parallel capacitor
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321 QQQQ 
321 VVVV 
11
VCQ 
𝐶 𝑇 = 𝐶1 + 𝐶2 + 𝐶3

15. Series capacitor
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321 VVVV 
𝐶 𝑇 =
1
1
𝐶1
+
1
𝐶2
+
1
𝐶3
321 QQQQ 

16. Group Work
Question 1. Find the total capacitance of
the three capacitors connected in parallel
with a 24-V battery.
𝐶 𝑇 = 𝐶1 + 𝐶2 + 𝐶3
𝐶 𝑇 = 2𝜇𝐹 + 4𝜇𝐹 + 6𝜇𝐹
𝐶 𝑇 = 12𝜇𝐹
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17. Question 2. Find the total capacitance of
the three capacitors connected in series with
a 24-V battery.
𝐶 𝑇 =
1
1
𝐶1
+
1
𝐶2
+
1
𝐶3
𝐶 𝑇 =
1
1
2𝜇𝐹
+
1
4𝜇𝐹
+
1
6𝜇𝐹
𝐶 𝑇 = 1.09𝜇𝐹
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18. Thank You for your listening
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