102.9 Principles of Electricity
Rectifier
Changes alternating current to direct current
Inverter
Changes direct current to alternating current
Circuit
Closed path through which electrons travel to operate an appliance
Cord
Combination of conductor and insulator
Fuse
Contains fine metal wire that allows current to flow through it, if overload occurs, it will heat up and wire will melt, breaking the circuit. Cannot be reused.
Cord Safety
Cords on appliances should be kept straight and free of knots, kinks and tangles to prevent breaks
Short Circuit
Dropping an electrical appliance into water, making it a foreign conductor, causes a:
Open Circuit
Electron flow is broken
Alternating Current
Electrons flow first in one direction and then the other
Direct Current
Electrons move at an even rate in only one direction
Too many appliances use same wall socket (overload)
Fires in electrical circuits can occur if:
Battery
Has positive and negative terminals, produces direct current only
Conductor
Material that best transports electricity; safely contained in an insulator
Watt
Measure of energy (power) used per second
Overload
More current flows in the line than it is designed to carry
Electrons
Most of the electricity you use daily consists of a flow of tiny, negatively charged particles called:
Short Circuit
Occurs when a "foreign conductor" comes in contact with a wire carrying a current to a load (appliance)
Fire Extinguishers
P: Pull pin A: Aim hose at base of fire S: Squeeze handle to begin flow S: Spray chemical discharge back and forth over fire
Closed Circuit
Path of electron flow to an appliance
Generator
Power source most often used in salons, produces alternating current, uses mechanical energy to produce flow of electrons
Parallel Wiring
Powers several loads at once or at different times
Source
Provides the force to move electrons through a conductor (Generators and Batteries)
Ground Fault Circuit Interrupter (GFCI)
Recommended for areas where water and electricity could come in contact
Ohm
Resistance; measures how difficult it is to push electrons through a conductor
Circuit Breaker
Reusable safety device that breaks the flow of current when an overload occurs. Contains two pieces of metal that make contact with each other; the pieces of metal conduct electric current. If current flow is too high, heat-sensing device causes the two pieces of metal to separate and the circuit is broken.
Series Wiring
Runs all loads at the same time (Example: Xmas tree lights; if one string is malfunctioning the electrical circuit cannot flow to the next string, the malfunction causes an open circuit)
Two conditions necessary for an electric current:
Source and Circuit
Appliance Nameplate
Tells frequency, volts needed, watts appliance consumes per second and UL rating (Underwriters Laboratories)
Electric Current
The flow (or movement) of electric charge, the charge is carried by electrons
Closed Circuit
When a blow dryer is on and air begins to flow, you have an example of a:
Kilowatt
1,000 watts
Grounding
2-plug or prong system (two slots of different sizes that keep electric current directed), 3-plug or prong system (offers most protection)
Direct Current
A current in which electrons move at an even rate and flow in only one direction is known as a:
Insulator
A material that does not allow a current to pass through it
Electricity
A powerful and important form of energy that produces light, heat, magnetic and chemical changes
Loads
A technical name for any electrically powered appliance
Volt
Unit of electric pressure; measures how hard electrons are being pushed by the source
Amp
Unit of electric strength; indicates number of electrons flowing on a line
Put water on it
What should NOT be done if a fire results from an overload of an electrical circuit?
Overload
When too many appliances are put on one circuit and are operated at the same time, more current flows than the line is designed to carry. This is known as:
Circuit Breaker
Which device breaks the flow of current when an overload occurs?
Alcohol
Which material does NOT allow a current to pass through it?