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CAPACITOR

• A capacitor is usually named after the dielectric material used.

• One of the simplest types of capacitors consists of two equally but oppositely charged parallel conducting plates separated from each other by a thin sheet of insulating material or dielectric

Dielectric

• An insulating material, or a very poor conductor of electric current.

Capacitance

• It is the ability of a capacitor to store charges.

Farad (F) named after Michael Faraday

The SI unit of capacitance

bigger & greater

The capacitance of a parallel plate capacitor is affected by the following factors:

1. The area of the plates. The _____ the area of plates, the _____ the capacitance

closer & greater

The distance between plates. The _____ the plates to each other, the ____ the capacitance.

higher & greater

The insulating material or dielectric between them. The capacitance is determined in terms of the material’s permittivity constant ε - the _____ the ε, the ______ the capacitance.

Combination of capacitors

Capacitors may be connected in series or parallel

Series Circuit

All components are connected end-to-end to form a single path for current flow.

Parallel Circuit

A circuit that has two or more paths for the electricity to flow, the loads are parallel to each other

Electric Current

The amount of charge passing through any point in a conductor per unit time

True

(T/F)

• When electrons were discovered, it became clear that the current in a metallic conductor is actually a flow of electrons from a negative terminal to positive terminal.

Electron Flow

Conventional flow: + -> –

________: – -> +

Direct Current

Travels in one direction (at all times)

Alternating Current

Travels in both directions 60 times in 1 second.

Direct Current

the voltage is always constant, and the electricity flows in a certain direction.

Alternating Current

the voltage periodically changed from positive to negative and from negative to positive, and the direction of the current also periodically changed accordingly.

Ohm’s law

Current in a circuit is directly proportional to the electric potential difference impressed across its ends and inversely proportional to the total resistance offered by the external circuit.

Electrical Resistance

Opposition of a material to the flow of electric current.

Electrical Conductivity

A physical property of a material that determines the ease by which electric current flows through it when subjected to an electric field. In some materials, the current density.

Cross Sectional Area

Resistance varies inversely from the cross-sectional area A of the wire. As the area increases, the resistance decreases. Thus, a thick wire has a lower resistance than a thin wire. A perfect analogy for this relationship is a road. The wider the road, the less “resistance” it will offer to the flow of traffic along it. 

Length

• The resistance of a wire is directly proportional to its length. A longer wire has greater resistance than a shorter wire of the same material and cross-sectional area. Using the road analogy, the longer the road, the more a “delay” in traffic is experienced.

greater

A longer wire has ______ resistance than a shorter wire of the same material and cross-sectional area.

Material of the wire

The effect of the kind of material on the resistance of the wire is determined by its resistivity.

True

(T/F)

As temperature increases, resistance and resistivity increases for conductors and decreases for insulators and semiconductors

Ammeter

device for electric current

Voltmeter

device for volts

Ohmmeter

device for resistance

Multimeter

device for electric current, volts, and resistance

pi

3.1416

Micro

x10^6

Nano

x10^-9