LESSON 01 – TERMINOLOGY & BASICS

LESSON NOTE

What is electricity?

It is electric current that results from the movement of electrons from a negatively charged point to a positively charged point.

What are conductors, insulators and semi-conductors?

Conductor: A material that allows an electric current to pass through it. (ie: silver, copper, aluminum)

Insulator: A material that does not allow electricity to flow through it easily. (ie: glass, wood, plastic)

Semiconductor: A material whose electrical conductivity can be controlled. (ie: silicon, germanium)

What is resistance?

It is material's opposition to the flow of electric current. It is measured in ohms.

Conductors have little resistance while insulators have high resistance.

What is electric current?

It is the rate of flow of an electric charge. It is measured in amps.

One amp equals one coulomb per second. One coulomb is the charged carried by 6.25 x 10¹⁸ electrons (which is a massive amount of electrons).

What is voltage?

The force which pushes electricity through a wire or any substance. Its unit is the volt.

Voltage is measured as a difference in potential between two points. It is also called electromotive force, potential, potential difference, or voltage drop.

What is Ohm’s Law?

Ohm’s Law states that the voltage drop (V) in a circuit is equal to the current (I) times the resistance (R).

V = I x R

Therefore, if we know the resistance of a material and the desired current, we can calculate the force (voltage) required.

Ohm’s Law can be applied over a single load or over entire sections of circuits.

What is AC? What is DC?

AC stands for Alternating Current. DC stands for Direct Current.

An alternating current (AC) is an electrical current whose magnitude and direction vary cyclically, as opposed to direct current, whose direction remains constant. The usual waveform of an AC power circuit is a sine wave. (Source: Wikipedia)

Batteries are sources of DC. Wall outlets are sources of AC.