D1 Flashcards
Define: Work
force x distance
Describe: Charge
Symbol used in formula: Q
Electrical Unit: Coulomb
Measured Unit: C
Describe; Power
Symbol used in formula: P
Electrical Unit: Watt
Measured Unit: W
Describe: Resistance
Symbol used in formula: R
Electrical Unit: Ohm
Measured Unit: Greek letter omega
Describe: emf or PD
Symbol used in formula: E
Electrical Unit: Volt
Measured Unit: V
Describe: Current
Symbol used in formula: I
Electrical Unit: Ampere
Measured Unit: A
P or pico
10^-12
N or nano
10^-9
u or micro
10^-6
m or milli
10^-3
k or kilo
10^3
M or mega
10^6
G or giga
10^9
one horsepower
746 watts
formula for motor efficiency
output watts/input watts x 100 = efficiency %
Energy =
power x time
Unit: Kw h
Define: Matter
anything that occupies spaces or has mass
Define: Element
contains atoms of only one type
Define: Compound
contains atoms of more than one type
Define: Atom
smallest unit into which and element can be broken and still possess the properties of that element
Define: Molecule
smallest independent unit which a substance can be broken and still retain the properties of that substance
Atomic number
of any element is always equal to the number of protons in its nucleus
valence shell or orbital
is the outer orbital of an atom
how many electrons in can a valence orbital hold?
8
Stable octet
when an atom has eight electrons in the valence shell.
How many valence electrons do conductors have?
from 1 to 3
How many valence electrons do insulators have?
from 5 to 8
How many electrons do semi-conductors have?
exactly four
anion
negatively charged atom
cation
positively charged atom
First law of charged bodies states that
Like charges repel and unlike charges attract
Polarity
charge at one point with respect to another
List three ways bodies become charged
Friction
Conduction
Induction
List the useful applications of electrostatic charge
Painting Sandpaper manufacturing Smoke precipitator Air filters Xerography
List two hazards of electric charge
Lighting
Spark while refueling a vehicle
The direction of electron flow
negative to positive in the circuit
positive to negative in the source
List the six ways to produce emf
Friction Chemical Pressure Heat Light Magnetism
Define: triboelectric effect or friction
two dissimilar materials are rubbed together, one material can transfer some of its electrons to the other
Define: electrochemical effect
when a chemical process is used to produce electricity. example: batter
Define: piezoelectric effect
Mechanical stress of a crystal causing displacement of electrons. example: weigh scale pad
Define: thermoelectric effect
when a junction of two dissimilar metals is heated. example: thermocouple use to sense temperature
Define: photovoltaic effect
when photons of light strike the surface of some materials causing the electrons to flow.
Define magnetoelectric effect
used to produce electricity that is used in homes and business
A Coulomb equals
6.24 x 10^18 electrons
Ohm’s Law
E = I X R
Watt”s Law 1
P = E x I
Watt’s Law 2
P = I^2R
Watt’s Law 3
P = E^2/R
Ohm’s Law direct proportion
if the applied voltage is doubled, the current will also double
Ohm’s Law inversely proportional
if the resistance is doubled, the current will decrease to half of its previous value.
Pictorial diagrams
Components are drawn as they appear
Components are in their actual circuit position
Three- dimensional
One-line diagrams
Components show their name, type, and #
not used to show actual position of components
single lines do not show return path for curcuit
Wiring diagram
show the actual location of components
components are shown in symbol form
show how it is wired
Schematic diagrams
shows electrical relationship but no physical
shows how the circuit works not how it looks
List three basic parts of a circuit
source
load
conductors
Define: Short circuit
parallel path of low resistance
Voltmeters hookup in
parallel with the device in which the voltage is to be measured.
have high resistance so no current will flow the meter.
Ammeters hook up in
series with the circuit
have a low resistance shunt so all the current will flow through the meter
List three types of fixed resistors
wire-wound
film resistor
carbon-composition
In what units is a resistor rated
in ohms and watts
what is a trip-free breaker
it cannot be prevented from tripping by holding the handle in the ON position
Define: Ductility
ability or a material to be drawn in to a wire
Define: Malleability
ability of a material to be rolled or hammered into thin sheets
Define: Ultimate strength
amount of mechanical stress a wire will withstand before breaking
Bunch stranded wires are generally used for
flexible cords
XLPE or X Link
Cross-linked or polyethylene
Which colour is used for grounding
Bare or green
Which colour is used for neutral
White or natural grey
Which colour is can be used for high side or the hot wire
Yellow
Blue
Red
Black
CEC defines low voltage as
31V to 750V
