Basic Electricity

What You Need to Know

Structure of an atom

Neutron

Proton

Electron

Shell or energy level

13 P14 N

Bohr model of the aluminum atom

13=13

Protons = Electrons

Net charge is neutral or zero

Placement of electrons in a copper atom

+29

Complete with 2

Complete with 8

Complete with 16

Incomplete with 1

Electricity-the flow of free electrons

Bound electron Free electron

Valance electron

Negative source

Positive source

Atomic structure of conductors, insulators, and semiconductors

Insulator - full valence shell

Conductor - 1 to 3valence electrons

Semiconductor - 4valence electrons

Sources of Electricity

• Heat

• Light

• Pressure

• Mechanical Magnetic action

CURRENT - The rate of flow of electrons

MeasurementPoint

AWG WIRE SIZES

The larger the gauge number the smaller the actual diameter of the conductor.

CONDUCTOR FORMS

Solid wire

Stranded wire

Large stranded cable

Multiconductor cable

Lamp cord

Ohm’s LawMost Important Law of Electricity

• This law outlines the relationship between voltage, current and resistance in an electrical circuit.

• Expressed as an equation: 1. I= Current in Amperes

2. E= is the potential difference measured in Volts

3. R= is the resistance measured in Ohms

                                                                            

Circuit Protection

• Fuses

• Circuit breakers

Ground Fault Interrupter

• Ground fault interrupters are designed to protect from electrical shock by interrupting a household circuit when there is a difference in the currents in the "hot" and neutral wires. Such a difference indicates that an abnormal diversion of current from the "hot" wire is occurring. Such a current might be flowing in the ground wire, such as a leakage current from a motor or from capacitors. More importantly, that current diversion may be occurring because a person has come into contact with the "hot" wire and is being shocked. When a circuit is functioning normally, all the return current from an appliance flows through the neutral wire, so the presence of a difference between "hot" and neutral currents represents a malfunction which in some circumstances could produce a dangerous or even lethal shock hazard