Electricity Skill Trades 1201. Parts of An Atom Electrons are negatively charged particles that orbit around the nucleus. Protons are positively charged.

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:GoldCopperAluminumWater

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 asE = I * R

WhereE is Electromotive Force measured in Volts I is Electrical Current measured in AmperesR is Electrical Resistance measured in Ohms

Ohm’s Law

E

I R

Calculation

Using Ohm's Law equation, calculate Resistance, where:E = 120 volts, I = 15 amps

Answer:R = E/IR = 120 v / 15aR = 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

I E

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

SeriesA single path for current to flow.

ParallelA single voltage shared by multiple loads.

ComplexCombinations of series and parallel circuits.

Series Circuit

_

+

R1

R2

R3

EI

Simple Parallel Circuit

_

+R1 R2E

I

I1 I2

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