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79 Cards in this Set

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  • Back
Form of Energy that travels invisibly through conductors
Electricity
Most Versatile form of energy
Electricty
Tiny negative charges that orbit the nucleus of an atom
Electrons
A material that allows an easy flow of electrons.
Conductor
Give some examples of good conductors
Silver, Copper, aluminum
A material that resists the flow of electrons
Insulator
Give some examples of insulators
Rubber, plastic, ceramic
A loop of conductor that takes electricity from its source to the load and back to the source
Circuit
Anything in the circuit such as a heater, a light, or a motor, that uses power
load
A steady-flowing type of electricity, produced by batteries and used in flashlights, boom boxes, and computers
DC (direct current)
A type of current that changes direction many times per second.
AC (alternating current)
What is AC mainly used in?
home wiring because it can be transported long distances over transmission wires.
A branch of science that deals with complicated uses of electricity, such as in radios, televisions, and computers
Electronics
the amount of electrons flowing through a conducting material
electric current
the amount of power consumed by an electrical device
electric power
A force that affects the rate at which electricity flows through a conductor. AKA electrical pressure
Voltage.
Why is higher voltage more dangerous?
The higher the voltage, the more likely it is to "leak" across an insulator or an air gap
Tells how much electrical pressure is used in a part of the circuit
Voltage drop
The # of complete alternations (from one direction to the other and then back again) that the alternating current makes per second.
Frequency
The term used to decribe a complete alternation from one direction to the other and then back again.
Cycle
The opposition of a material to the flow of electricity through it.
Resistance
T/F
All circuits must have resistance.
True, if they do not, they are called short circuits and the wires will overheat
Describes the relationship between electrical pressure (voltage), current strength (amperage), and resistance (ohms) in any circuit
ohm's law
What is the fomula for Ohm's law?
Amperes = volts/ohms
What is the unit of measure for electric current?
Ampere
unit of measure for electric power
watt
Unit of measure for electric current or strength
Ampere
unit of measure for electric pressure or voltage
volt
Unit of measure for electric resistance
Ohm
Unit of measure for electric frequency
Hertz
What measuring device is used to measure electric power?
electric meter
The amount of power consumed by an electrical or electronic device can be calculated using which formula?
The law of electric power

watts = volts x amperes
Describe how an electromagnet works.
A current passing through a conductor creates a magnetic field around it. Conductor wire is wrapped around an iron core
Two electromagnets placed next to each other
Transformer
Which type of transformer has more turns of wire on the output side?
Step-up transformer
Which type of transformer has more turns of wire on the input side? What is the relationship between output and input voltage in this type of transformer?
A step-down transformer.

The output voltage is smaller than the input voltage.
Changes rotating (kinetic) energy into electric energy
Generator
Changes electric energy into kinetic energy
Motor
What are the names of the two magnets which make up a motor
Rotor and Stator
An magnet (usually an electromagnet) which spins inside of the stator in an electric motor
Rotor
A fancy name for stationary magnet inside of a motor
Stator
Explain how an electric motor works
A rotor spins inside a stator. Usually, the rotor is an electromagnet. When electricity is fed to the rotor, the rotor starts to turn and the rotor and stator repel each other, forcing the rotor to keep spinning. The rotor changes polarity at the point where the magnets would stop repelling.
A device that can briefly store electricity
capacitor
What is the symbol for a capacitor
sort of looks like this:

---l(---
What does the symbol for a resistor look like?
sort of like this:

---^v^v^v---
What does a transformer do?
Changes the voltage and amperage of a current
How does a transformer work?
It works by changing electricity into magnetism, then back into electricity.
How many coils does a transformer have?
2
What is the role of each coil in a transformer?
One gets current from a source, and the other supplies output.
Stores chemical energy that can be readily converted into electric current. They can be either wet or dry
Battery
What type of current does a battery always produce?
DC
How does a battery produce electricity?
Electrochemical reactions between the cathode and the carbon electrode at the center result in free electrons, which can travel through a circuit to make electric current
In this type of circuit, all moving electrons pass through every part of the circuit, including all the loads and swithches.
Series circuit
In a series circuit, what must the total voltage of the loads equal?
The voltage of the circuit.

For example, In a series circuit supplied by a 12 volt battery, the total volt drop of the loads (such as a light bulb, etc.) must have a 12 volt drop.
A String of christmas tree bulbs is a good example of what type of circuit?
Series Circuit.

If one bulb goes out, then the voltage drop of the load is less than that of the circuit, thus the whole string goes out.
In this type of circuit, the loads are placed between the two supply wires, so that they all get the same voltage.
Parallel circuit
What is the advantage of a parallel circuit over a series circuit?
Current can flow through any of the loads, even if one is switched off.
Current is the same at all points in a _________ circuit and voltage is the same at all points in a _________ circuit
Series, parallel
How do you find the total resistance in a series circuit?
add the resistance of each load.
This type of circuit combines the features of series and parallel circuits
Series-parallel circuit
These types of circuits are found throughout a house. they bring power to lights and outlets.
Series-parallel circuits
Silicon is an example of this. It can act as a conductor or as an insulator.
Semiconductor
Chemicals called ________ are applied to silicone to determine whether it will act as an insulator or as a conductor.
dopants
How do dopants determine whether or not a semiconductor will act as an insulator or as a conductor
They make electrons available (conductor) or not available to flow (insulator)
Devices that acan switch a current, regulate its flow, or amplify a current, all based on the presence of a smaller current.
transistor.
Millions of tiny transistors and diodes built on a piece of semiconductor describe the basis for what?
computer logic and memory
Diodes are used in these devices which convert AC to DC.
Rectifiers
What are the 2 functions of the fuse or circuit breaker box in a home?
Breaking up the load in the building into a number of circuits, and preventing current from flowing into the circuits.
Many simple circuits have two types of conductors, what are they, and what are their colors?
hot conductor is usually black, and the grouded conductor is white.
together, what are the black and white wires of a simple circuit called?
supply wires
For safety, what should you do to work on any electric circuit?
Shut off the fuses and circuit breakers and check that the electricity is off. Use an electrical tester to test whether the hot wires are energized.
15 ampere circuits require which guage of wire? 20 ampere circuits?
15 amps requires 12 guage wire. 20 amps require 12 guage wire. (remember that bigger, heavier wires carry more current)
Electricity always wants to complete a circuit. In building wiring, what are the two paths electricity can take to get back to the source (fuse box or circuit breaker)
In normally returns through the grounded wire, but if something goes wrong with that line, it will return through the bare equipment grounding.
Why are modern electric plugs polarized?
because the two supply wires are different (black brings the current and white drains it away).
2 of these can work together to control a circuit at either of 2 locations (such as the top and bottom of stairs)
3 way switches
This is used to continuously control voltage and dim lights
rheostat
In home wiring, ________ always controls the hot side of the circuit (the one that supplies the current)
switches
What is the job of either a circuit breaker or a fuse?
breaking the circuit (cutting of the power) when something goes wron.
These types of cables, usually used in TV's have an inner and outer conductor.
Coaxial cable.