electricity skill trades 1201. parts of an atom electrons are negatively charged particles that...
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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