CHAPTER 2 CAPACITOR DIELECTRIC STUDENT

CHAPTER 2

CAPACITOR & DIELECTRIC

Subtopics

2.1
2.2
2.3
2.4

Capacitance, Capacitor in series & parallel
Charging & discharging of capacitors
Capacitors with dielectric
Energy stored in a charged capacitor

2.1 Capacitance, Capacitor in series & parallel
Learning Outcomes:
At the end of this topic, students should be able to:
 Define capacitance
 Use the capacitance formula
 Determine capacitance of parallel plate
 Deduce & calculate the effective capacitance of capacitors in series &

parallel

2.1.1 Capacitor
 capacitor is electric component to store electric charge



it is consists two conducting plates separated by a small air gap or a thin insulator (called dielectric such as mica, ceramics, paper)



the conducting plates could be in the shape of :
i. cylindrical ii. spherical iii. parallel plate

2.1.1 Capacitor
 symbol

2.1.1 Capacitor
 uses of capacitor:

- capacitors are commonly used in many electronic circuits
i. Photoflash unit ii. Giant lasers iii. Computer keyboard

2.1.1 Capacitor
Capacitance, C
 the ability of a capacitor to store charge is measured by its capacitance
 defined as the ratio of the charge, Q on either plate to the potential

different, V between them

Q
C
V
 unit: Farad (F)

Q : magnitude of the charge on each plate
V : potential difference across the two plates

Exercise 1

1) When a potential difference of 24 V is applied across a capacitor, the charge on the capacitor is 120 μC. Determine the capacitance of the capacitor [Ans : 5x10-6]
2) Determine the charge on a 300 pF capacitor when it is charged to a voltage of
1.0 KV
[Ans : 3x10-7]
3) Determine the potential difference across a capacitor with 235 μC and
526 nF
[Ans : 446.8]

2.1.2 Capacitor in series & parallel

CAPACITORS

(1) Series

(2) Parallel

2.1.2 Capacitor in series & parallel

Capacitors in series
Figure shows three capacitors are connected in series to a battery of voltage, V

2.1.2 Capacitor in series & parallel

Capacitors in series
The