Unit 17

"_____" is a property of an electrical circuit that enables it to store electrical energy by means of an electric field and to release this energy at a later time.

Capacitance

When a capacitor has a potential difference between the plates, it is said to be _____. One plate has an excess of free electrons, and the other plate has a lack of them.

Charged

To discharge a capacitor, all that is required is a(n) _____ path between the terminals of the capacitor. The free electrons on the negative plate then flow through the external circuit to the positive plate.

Conductive

Factors that determine the capacitance of a capacitor are the _____ the plates.

Dielectric between, the surface area of, and the distance between

True or False: A half-wave rectifier can be used to convert ac voltage into dc voltage to continuously charge a capacitor.

False

A capacitor is a device that resists changes in current. Because a capacitor introduces reactance to the circuit, it shifts the current waveform to _____.

Lead the applied voltage by 90 degrees

If a capacitor is overcharged, the electrons from the negative plate can be pulled through the insulation to the positive plate. The capacitor is said to have _____.

Shorted (Or broken down)

True or False: Capacitors are used to start single-phase ac motors and to prevent arcing across the contacts of electric switches.

True

True or False: Even when power is removed from the circuit, capacitors can store large amounts of energy for a long period of time, and can discharge and arc if inadvertently shorted or grounded out.

True

The opposition offered to the flow of alternating current by a capacitor is called "capacitive reactance," is expressed in ohms, and abbreviated _____.

Xc