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11 – Capacitance - 1

In this chapter, we are going to talk about capacitance. We need to make a
distinction between the capacitor and capacitance. A capacitor is a device, whereas
capacitance is an electrical property. First, we will discuss the capacitor and then the
property of capacitance.

Figure 11-1 Construction of a capacitor
As you can see, a capacitor is a two-terminal device. Two conductive plates
separated by an insulator. This should suggest to you that the current never flows
through a capacitor.

Capacitor types generally take their name from the type of insulation material used
between the plates. This is called the dielectric of the capacitor. Some capacitors
have their dielectrics electrically formed. These capacitors are said to be polarised
in that they have a positive and negative terminal. When connected in a circuit, this
polarity must be maintained, if not, the dielectric will be destroyed and the capacitor
could gas and explode.
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