Everything Electricity Flashcards
Name the three principal parts of an atom
Electron, proton, and neutron
A(n) ________ is a substance that cannot be chemically divided into two or more simpler substances
Element
All ________ is made from a combination of atoms
Matter
The atomic number of an element is equal to the number of ________ in the nucleus
Protons
Any electrons located in the outer shell of an atom are known as ________
Valence electrons
A conductor is made from a material that contains between ________ valence electrons
One to three
Materials containing seven or eight valence elctrons are known as ________
Insulators
________ are materials that are neither good conductors nor good insulators
Semiconductors
The smallest part of a compound is called a ________
Molecule
List the six methods for producing electricity
Magnetism, chemical action, pressure, heat, friction, and light
A(n) ________ is the smallest part of an element
Atom
State the law of charges
Opposite charges attract, while like charges repel
It is theorized that protons and neutrons are actually formed from a combination of smaller particles called ________
Quarks
True or false: Static charges accumulate on insulator materials
True
The word ________ means not moving or sitting still
Static
A current of 1 ampere delivered in one second is defined as ________
1 coulomb
The ampere (A) is equal to ________
1 coulomb per second
The electron flow theory states that current flows from the most ________ point in the circuit to the most ________
Negative to positive
The conventional current flow theory states that current flows from the most ________ point to the most ________
Positive to negative
Voltage can also be referred to as ________ and ________
Potential difference and electromotive force (EMF)
A volt is the amount of potential necessary to cause ________ to produce ________ of work
1 coulomb, 1 joule
A(n) ________ is the unit of resistance to current flow
Ohm
The amount of power being used in a circuit is measured by which unit
Watts
________ can be neither created nor destroyed, only transformed
Energy
________ is equal to power (kW) x time (hours)
Energy
________ is the transfer of energy from one object to another
Work
State Ohm’s law
Current is directly proportional to the voltage and inversely proportional to the resistance
1 watt equals ________
1 joule / second
True or false: An open circuit has infinite resistance
True
Before current can flow, a circuit must be ________
Complete / closed
A ________ circuit has little or no resistance
Short
What is a coulomb?
A coulomb is a measure of charge. It is defined as the charge transferred by a current of 1 ampere in one second
What is an ampere?
An ampere is equal to 1 coulomb per second
True or false: when current flows through a wire, a magnetic field is created around the wire
True
True or false: the direction of current flow through a wire determines the polarity of the magnetic field
True
List two common functions of resistors in a circuit
Limit the flow of current through a circuit and produce a voltage divider
________ resistors have only one ohmic value
Fixed
List 5 types of fixed resistors
Composition carbon, metal film, carbon film, metal glaze, and wire-wound
A ________ is a resistor whose values can be changed or varied over a range
Variable resistor
How many terminals are there in a rheostat?
Two
A potentiometer is a variable resistor that contains ________ terminals
Three
True or false: the value of fixed resistors can be varied
False
The primary advantage of wire-wound resistors over other fixed type resistors is their ________
High power rating
Name three types of fixed resistors
Carbon composition, carbon film, metal film, metal glaze, and wire-wound
How should a tubular wire-wound resistor be mounted and why?
Vertically. Air flow helps dissipate heat thereby keeping the resistor from over-heating
What is a potentiometer?
A three terminal variable resistor
A resistor has colour bands of orange, blue, yellow, and gold. What is the resistance and tolerance of this resistor?
360,000 ohm, +- 5%
A ________ is a circuit that has only one path for current to flow
Series circuit
True or false: fuses and circuit breakers are connected in series with the rest of the circuit
True
State the three rules that can be used with Ohm’s law for finding values of voltage, current, resistance, and power in any series circuit.
- The current is the same at any point in the circuit (It = I1 = I2 = I3 …)
- The total resistance is the sum of the individual resistors (Rt = R1 + R2 + R3 ….)
- The applied voltage is equal to the sum of the voltage drops across all the resistors (Et = E1 + E2 + E3 …)
True or false: current is the same at any point in a series circuit
True
The ________ in any circuit is equal to the sum of the power dissipated by all parts of the circuit
Total power
When multiple voltage sources are connected in series, the ________ pole of one source always connects to the ________ pole of another source
Positive to negative
When series circuits are used for the purpose of obtaining different voltages from one voltage source, they are known as ________
Voltage dividers
________ are circuits that have more than one path for current to flow
Parallel circuits
True or false: In a parallel circuit, the total current flow is equal to the sum of the currents through all the branches
True
True or false: The amount of current flow through each branch of a parallel circuit is inversely proportional to it’s resistance
True
What characterizes a parallel circuit?
A circuit that has more than one path for current to flow
Four resistors having a value of 100 ohm each are connected in parallel. What is the total resistance of the circuit?
25 ohm. Rt = R/N, Rt = 100/4, Rt = 25 ohm
Describe the two key rules that must be followed when connecting voltage sources in parallel
- Voltage sources connected in parallel must have the same voltage rating
- Care should be taken to match polarities, positive to positive and negative to negative
True or false: All parallel circuits are current dividers
True
________ states that at any node, the algebraic sum of the currents will equal zero
Kirchhoff’s current law
State Kirchhoff’s voltage law
In a closed circuit, the algebraic sum of the voltage sources and voltage drops must equal zero
________ are circuits that contain both series and parallel branches
Combination circuits
One of the most common analog meter movements is the ________ , also known as the moving-coil meter
D’Arsonval movement
Name the 4 components of the d’Arsonval meter movement
A permanent magnet, pointer, spring, and moving coil
Voltmeters have a very ________ resistance and are designed to be connected directly across the ________
High, source
Ammeters have a ________ resistance and must be connected in _________ with a load to limit the flow of current
Low, series
________ are used to measure the resistance in a circuit
Ohmmeters
True or false: It is safe to connect an ohmmeter, whether digital or analog, to a circuit when the power is turned on
False. Ohmmeters use their own internal power supply and have a very low operating voltage. Connecting an ohmmeter to power will probably damage or even destroy the meter
Name the four factors that determine the resistance of a length of wire
Material, diameter, length, and temperature
Materials that increase their resistance with an increase of temperature have a ________ temperature coefficient
Positive
Materials that decrease their resistance with an increase of temperature have a ________ temperature coefficient
Negative
A ________ is a cell that cannot be recharged
Primary cell
True or false: A secondary cell can be recharged
True
The amount of current a particular type of cell can deliver is determined by ________
The surface area of its plates
The amount of energy a cell can deliver is called its ________
Current capacity
The device produced by the joining of two dissimilar metals for the purpose of producing electricity with heat is called a ________
Thermocouple
________ is produced by some materials when they are placed under pressure
Piezoelectricity
A ________ converts chemical energy into electrical energy
Voltaic cell
A ________ is a group of cells connected together
Battery
The amount of energy a battery can contain is called its ________ or ________
Current capacity, energy density
A ________ is a device for measuring the specific gravity of an electrolyte
Hydrometer
When lead-acid batteries are charged, ________ is produced
Hydrogren gas
True or false: When cells are connected in series, their voltages remain the same and their ampere-hour capacities add
False. When voltages remain the same and ampere-hour capacities add, cells are connected in parallel
True or false: It is safe to connect batteries of different voltages in parallel
False
The basic function of a ________ is to open and close a circuit
Switch
Switches have 6 possible ratings, 3 of which are mandatory on all switches regardless of their application. What are the 3 ratings?
Voltage, amperes, and CSA (Canadian Standards Association) approval
A SPDT switch is also known as a ________
Single pole double throw, or a three-way switch
A ________ is designed to prevent dangerous shocks and protects against over-current situations
Ground fault circuit interrupter (GFI)
A GFI unit is able to detect a leakage of current as low as ________
2 mA (0.002 A)
A ________ is a current sensitive device designed to limit current flow and protect the conductors in a circuit
Fuse
Ohm’s Law states that the current is directly proportional to the ________ and inversely proportional to the ________
Voltage, resistance
The kilowatt-hour is a unit of ________
Energy
The term ________ refers to the generation of electricity by pressure
Piezoelectric effect
The term triboelectric effect refers to the generation of electricity by ________
Friction
The device that generates electricity from the sun’s energy is called a(n) ________
Photovoltaic cell
The majority of electrical energy is produced by ________
Magnetism
What is the main advantage of using stranded wire versus solid wire
Flexibility
What are the common problems associated with aluminum when using it as a conductor?
Oxidization, cold flow (similar to annealing), and electrolysis
What is the moisture absorbing effect of varnished cambric called
Hygroscopic
What is the main advantage of using MI cable?
High heat resistance
MI Cable has a common ‘trade name’ known as ________
Pyrotenex
Conductors that lay flat and typically run underneath carpet are classified as ________
FCC, flat conductor cable
A conductor labelled ‘ACWU’ is suitable for use in ________ and ________ environments
Wet, underground
________ is a property that describes the ability of a material to be stretched, pulled, or drawn into a thin wire or thread without breaking
Ductility
________ refers to the ability of a conductor to carry current
Ampacity
The ampacity of a conductor is determined by these 3 factors
Material, size (or area), and insulation
________ is one of the most common insulator materials used for residential and industrial wiring
Thermoplastic
What type of insulation is used on wire in the manufacture of windings for transformers, motors, and relays?
Enamel insulation
A ________ is a variable resistor with 3 terminals
Potentiometer
1 mil equals ________ inches
0.001, (1 one-thousandth)
A substance that is made of atoms of more than one type is a ________
Compound
Anything that occupies space or has mass is referred to as ________
Matter
The atomic number of an element refers to the number of ________ in the ________ of an atom
Protons; nucleus
The smallest part that a substance can be broken down into and still possess the same properties of the substance is a ________
Molecule
________ current is described as unidirectional
Direct
Alternating current is described as ________
Bidirectional
Why is it not recommended that an overcurrent device be installed in the neutral conductor of a three-wire circuit?
It may open and create unbalanced voltages across the loads
What is the main reason for grounding the midpoint (neutral point) of a 3 wire supply?
To reduce the shock hazard to less than line to line value
In a parallel circuit, increasing the number of branches will cause the circuit ________ to increase and the circuit ________ to decrease
Power; resistance
A common conductor insulation suitable for use in wet and dry locations is type ‘TW’. The letter ‘W’ indicates “wet” and the ‘T’ indicates ________
Thermoplastic
In “type NMD90”, what does the 90 refer to?
Temperature
The standard residential voltages of a three-wire system are ________
120V/240V
True or false: A three-wire cirucuit is said to be unbalanced when the line conductors carry equal currents
False. This describes a balanced three-wire circuit. Unbalanced three-wire circuits have line conductors that carry different values of current
In an unbalanced three-wire circuit, line one carries 7 amps and line two carries 13 amps. Using Kirchhoff’s Current Law, the current in the neutral carries how many amps?
6 amps
________ is the rate at which work is done
Power
