Electricity Skill Trades 1201

Parts of An Atom

Electrons are negatively charged particles that orbit around the nucleus. Protons are positively charged.

Opposite charges attract. Electricity occurs when electrons flow from one atom to another.

Voltage Voltage is a measure of the Electromotive Force (EMF) in electricity. EMF is the electric force that "pushes" electrons around a circuit.

Voltage Measured in volts (v). Algebraic Symbol: E or V Graphic Symbol: ~ _ +

Current Current is a measure of the rate of electron flow through a material. Measured in amps (a).

Current Algebraic Symbol: I = intensity Graphic Symbol: A

Resistance Resistance is the property of matter which opposes the flow of electrons. Measured in ohms (  ).

Resistance Algebraic Symbol: R Graphic Symbol:

Conductors Conductors have a large number of loosely attached electrons that can move very easily from one atom to another. Examples:  Gold  Copper  Aluminum  Water

Insulators Material with a high resistance to electrical current. Electron orbits are very close to the nucleus. Examples:  Plastic  Rubber  Glass  Wood

Electrical Circuit For electricity to flow, there must be a complete path. Therefore it must have:  Conductor (e.g. Copper wire)  Energy Source (e.g. Battery)  Load (e.g. Light)  Control Device (e.g. Switch)

Electrical Circuit

Ohm’s Law Ohms Law is a mathematical equation explaining the relationship between Voltage, Current, and Resistance.

Ohm’s Law The relationship is expressed as  E = I * R Where  E is Electromotive Force measured in Volts  I is Electrical Current measured in Amperes  R is Electrical Resistance measured in Ohms

Ohm’s Law E IR

Calculation Using Ohm's Law equation, calculate Resistance, where:  E = 120 volts, I = 15 amps Answer:  R = E/I  R = 120 v / 15a  R = 8 

Power Power is the ability of electricity to perform work. Measured in watts (W) Algebraic Symbol: P

Power Law The relationship is expressed as:  P = I x E Where…  P is Power measured in Watts.  I is Electrical Current measured in Amperes.  E is Electromotive Force measured in Volts.

Power Law P IE

Calculation Using Power equation, calculate Current (I), where:  E = 120 volts and P = 800 w Answer:  I = P/E  I = 800 w / 120 v  I = 6.67 amps

Types of Circuits Series  A single path for current to flow. Parallel  A single voltage shared by multiple loads. Complex  Combinations of series and parallel circuits.

Series Circuit _ + R1 R2 R3 E I

Simple Parallel Circuit _ + R1R2 E I I1I2

Electrical Tools Wire Strippers/Crimpers Insulated Screwdrivers

Electrical Tools Wire sheathing stripper Marrettes / Wire Nuts

Electrical Tools Lineman Pliers Needle Nose Pliers

Electrical Tools Octagon / Junction Box Switch Box

Electrical Tools

Electricity Skill Trades 1201