1
Science 9
Unit D – Electrical Principles & Technologies
Vocabulary Terms Concept 2
Static electricity
Proton
Electron
Neutral
Charge
separation
Electrical
discharge
Electrical
current
Circuit
Amperes (A)
Conductors
Load
Voltage
Potential
difference
Volt (V)
Voltmeter
Short circuit
Insulators
Fuses
Circuit breakers
Electrochemical
cell
Dry cell
Electrolyte
Ion
Electrode
Wet cell
Primary cell
Rechargeable
cell
Secondary cell
Battery
Electrolysis
Electrochemistry
Electroplating
Conductor
Insulator
Resistor
Resistance
Ohms (Ω)
Variable resistor
Rheostat
Ohm’s Law
Ammeter
Schematic
Schematic
diagram
Series circuit
Parallel circuit
Transistor
Microcircuit
Concept 2 – Energy Transfer
Learning Concept
 Assess the potential danger of electrical devices, by referring to the
voltage and current rating (amperage) of the devices
 Distinguish between safe and unsafe activities
2
__________________ aspects of electricity must be considered when
looking electrical dangers
o __________________
 The measure of ____________________________________
____________________________________ by each particle
o __________________
 The __________________ at which _______________
_______________________________________
____________________________________
is
__________________
dangerous than ____________________________________
Small voltages can __________________ if the shock carries a
______________________________________________________
o The
____________________________________
is
more
__________________ than voltage when assessing potential danger
50,000 V is more likely to kill than 10 V
0.001 A passed through your body won’t likely be felt
Current in the range of __________________ causes a _______________
_________________________________________________________
o Currents as low as _______________ can be __________________
__________________ (stun) guns can carry up to __________________
o Can deliver up to 1,500 V to a person’s body
Small current of ____________________________________
____________________________________
in
Canada
deliver
__________________ of electricity
A __________________ draws about __________________ while a
__________________ pulls __________________
o Possible to suffer ____________________________________ from a
____________________________________
3
Science Log
Make a list of 5 safety pointers for use with electrical devices
o ex. Do not use electrical devices when near or in water unless they are
specially designed
Learning Concept
Distinguish between static and current electricity
o Identify example evidence of each
Recall:
o The __________________ has a __________________ charge
o The __________________ has a __________________ charge
Most objects have ____________________________________ of positive
and negative charges, which makes them __________________
____________________________________ occurs when _________
___________________________ are brought __________________ to
____________________________________
Rubbing the balloon on your hair _________________________
___________ from your __________________ to the __________________
Bringing the charged balloon to the wall ___________________________
___________________________ but attracts the __________________
4
The Laws of Electrical Charges
o ____________________________________ each other
o ____________________________________ each other
Science Log
Illustrate the Laws of Electrical Charges
Opposite Charges
Like Charges
 ____________________________________
is
observed
as
a
__________________
 Static energy does not flow in a current but can _________
_____________________________________________
 __________________ build up in your body
 Doorknob becomes positively charged as “your” electrons
repel the doorknob electrons
 “Your” electrons are attracted to the doorknob’s protons
 While static energy __________________ and __________________, it
does not flow continuously
 ____________________________________
are
________________
____________________ of ____________________________________
 This is the type of energy used to operate electrical devices
5
Learning Concept
Identify electrical conductors and insulators
o Compare resistance of different materials to electric flow
__________________ do __________________ allow for easy transfer of
electrons away from the nucleus
o ________________________________ to the __________________
In a __________________ the electrons are more __________________
__________________ so they can __________________ from the nuclei
o Current will only flow if the __________________ is hooked to an
____________________________________
__________________ materials conduct electricity at different
__________________
o Important to know so devices designed are both
__________________ and __________________
A __________________ is a type of __________________
o Allows current to pass but ________________________
____________ to it
 Limits __________________ of electric current to pass
o __________________ is a __________________ of ________
____________________________ it is for electrons to flow through a
substance
Resistance is measured in __________________
o Symbol is the Greek letter __________________, ______
The __________________ resistance a substance has, the
____________________________________ is __________________ from
each electron passing through it
A ____________________________________
(lie detector) is an
application of resistance
o Measures ____________________________________, _________
___________________________ and __________________
6
Learning Concept
Use switches and resistors to control electrical flow
o Predict effect of these devices and others in an application
A __________________ is the best method for turning electricity
______________________________________________________
o Basic principle: when on, ____________________________________
are ____________________________________ and electrons can
__________________
o When off, the conductors are _______________________________,
and electron flow is __________________
A ____________________________________, or __________________, is
used to __________________ or __________________the amount of
current in a circuit __________________
o ____________________________________
o ____________________________________
o Foot-operated speed controls on sewing machines
Learning Concept
Describe, using models, the nature of electric current
Explain the relationship between current, resistance, and voltage
Recall:
o __________________ looks at ______________________________
an electrical charge is able to move (_________________)
o __________________ looks at _______________________________
charge is carried in the electrical current (__________________)
o __________________ is a measure of _________________________
it is for electrons to transfer (__________________)
7
The ____________________________________ has several components
o Water in the container
o Amount of water pouring from the spouts
o Force of gravity on the water
o Diameter of the spout
Learning Concept
Measure voltages and amperages in circuits
o Apply Ohm’s law to calculate resistance, voltage and current in
simple circuits
German scientist ____________________________________ proved a
__________________
link
between
__________________
(V),
__________________ (I) and __________________ (R)
Ohm’s law states that as long as __________________ remains the same
o __________________ of a conductor _________________________
o __________________ is directly __________________ to the
__________________ applied
So long as __________________ of the __________________ units are
known, the last one ____________________________________________
8
Science Log
Rearrange Ohm’s equation to solve for each of the unknown variables:
Ohm’s Law
Equation
Measured
with
Variable
Symbol
Units
Voltage
V
volts (V)
Voltmeter
Current
I
amps (A)
Ammeter
Resistance
R
ohms (Ω)
Ohmmeter
Example
An electrical stove is connected to a 240-V outlet. If the current flowing
through the stove is 20-A, what is the resistance of the heating element?
9
Example
A 30-V battery creates a current through a 15-Ω resistor. How much current
is created?
Example
A motor has an internal resistance of 40-Ω. The motor is in a circuit with a
current of 4.0-A. What is the voltage?
Example
A current of 625-mA runs through a bulb that is connected to 120-V. What
is the resistance of the bulb?
10
Learning Concept
Develop, test and troubleshoot circuit designs for a variety of specific
purposes
A __________________ is simply a _____________________________
_______ that ____________________________________ can flow through
o Often drawn with __________________ in an image known as a
__________________ or a _________________________________
Science Log
Using your textbook as a reference (pg 312) complete the following
diagram of electrical symbols
Symbol
Represents
Conductor
Cell
Battery
Lamp
Resistor
Switch
Ammeter
Description/Definition
11
Rheostat
Motor
Fuse
A __________________ circuit is one in which the current passes through
____________________________________
Science Log
Illustrate the three light bulbs in a series circuit using a schematic diagram
Disadvantages
o If the pathway is __________________ the whole circuit
__________________ function
o Adding components __________________ the ___________
_________________________
 Adding another bulb would make all the lights dimmer
Advantages
o Household circuits are wired so that it is __________________
____________________________________ the electricity in the
circuit
12
__________________ circuits have ___________________________
_________ for each section of the circuit
o Each bulb would have its own path to the current source
Science Log
Illustrate the three light bulbs in a parallel circuit using a schematic diagram
Advantages
o An
__________________
or
break
in
one
pathway
____________________________________ the rest of the pathways
o Adding ____________________________________ the total
resistance in the circuit
Learning Concept
Identify similarities and differences between microcircuits and circuits in a
house
Science Log
Define transistor
Define fuse
Use page 315 of your textbook to compare and contrast microcircuits and
household wiring