- Physics -
Approximately April 28th to May 16th
We will be discussing:
Electricity as a Fluid. (Accessed on 2014).
The Energuide Label (2009).
Embedded Hybrid Headphone (2007).
Uploaded by Natural Resources Canada. Available onlineUploaded
at:
by Cavalli Audio. Available online at:
Uploaded by Dr. Dadiv Stern Available online at: http://wwwhhttp://198.103.48.133/publications/infosource/pub/appliances/
http://www.cavalliaudio.com/diy/ehha/images/BasicAmpSimple
spof.gsfc.nasa.gov/Education/welectrc.html
2007/page2.cfm?attr=4
Schematic.gif
Your Experience with Atoms &
Elements:
Grade 7 – Particle Theory of Matter
Grade 6 – Electricity/Circuits
Use the textbook to review/learn
important vocabulary
Bill Nye Electricity
https://www.youtube.com/watch?v=ugt
HMtc08DM
Plutarch Model
- The “Air Model”
- Charged objects heat
the air around them
- Swirling air pushed
nearby objects towards
it
- Challenges?
Previous Models of Static Electricity. (Accessed on 2014). Uploaded by SJSD.
Available online at:
http://www.sjsd.net/~bhayward/Unit%203%20Electricity/2%20%20Models%20of%20Static%20electricity%20(3-02,%2004).pdf
William Gilbert Model
- The “Sticky Hand
Model”
- Thought a substance
called Effluvium came
from the charged
object and attached to
other objects
- Challenges?
Previous Models of Static Electricity. (Accessed on 2014). Uploaded by SJSD.
Available online at:
http://www.sjsd.net/~bhayward/Unit%203%20Electricity/2%20%20Models%20of%20Static%20electricity%20(3-02,%2004).pdf
Ben Franklin Model
- The “1-Fluid Model”
- All objects contain
electric fluid
- If an object gains fluid it
becomes positively
charged
- If an object loses fluid it
becomes negatively
charged
Previous Models of Static Electricity. (Accessed on 2014). Uploaded by SJSD.
Available online at:
http://www.sjsd.net/~bhayward/Unit%203%20Electricity/2%20%20Models%20of%20Static%20electricity%20(3-02,%2004).pdf
Charles Dufay Model
- The “2-Fluid Model”
- All objects contain
electric fluids
- If an object gains or
loses one of the fluids
(+ or -), it will
become charged
Previous Models of Static Electricity. (Accessed on 2014). Uploaded by SJSD.
Available online at:
http://www.sjsd.net/~bhayward/Unit%203%20Electricity/2%20%20Models%20of%20Static%20electricity%20(3-02,%2004).pdf
Particle Model
- Everything is made of atoms
- Protons, Electrons, Nuetrons
- An object becomes negatively charged by
gaining electrons
- An object becomes positively charged by
losing electrons
Previous Models of Static Electricity. (Accessed on 2014). Uploaded by SJSD.
Available online at:
http://www.sjsd.net/~bhayward/Unit%203%20Electricity/2%20%20Models%20of%20Static%20electricity%20(3-02,%2004).pdf
Particle Model
- Charges are not created or destroyed,
they are conserved
- When two materials come in contact, the
valence electrons transfer from one
material to the next
Previous Models of Static Electricity. (Accessed on 2014). Uploaded by SJSD.
Available online at:
http://www.sjsd.net/~bhayward/Unit%203%20Electricity/2%20%20Models%20of%20Static%20electricity%20(3-02,%2004).pdf
Persuasive Model Ad/Commercial
Groups of 3
(boys & girls)
Understanding of Electricity Intro
Page 294
Qs 2, 3, 6, 7, 13
- An electricity current
is the movement of an
electric charge
- Involves the controlled
movement of electrons
- For electrons to
transfer, a conductor
must be used to
conduct the charge
How It Works
- A charged object is brought towards a
conductor
- A charge separation is created on the
conductor
- Called polarization
- Think of how one side of a battery
displays (+) and the other displays (-)
How It Works (Cont.)
- The charge builds up & can be released
on a conductor in short bursts
- It is not a continuous release of electrons,
just enough to keep it going
- Once all the charges are released, the
current will stop
Electric Cells
- A type of device designed
to produce electrical
charges longer than what
was previously possible
with electrostaticallycharged objects
(ex) Volta cells, dry cells,
wet cells
Volta Cell/Wet Cell
- Two different metals
were placed in a salt
or acid solution
- The chemical reaction
caused sparks without
being recharged
Volta Cell/Wet Cell
- The salt solution
contains (+) Sodium
Ions & (-) Chlorine
Ions
- The Copper gives
electrons to the (+)
Sodium ions
- Copper becomes (+)
Volta Cell/Wet Cell
- The Zinc attracts the
(-) Chlorine Ions
- Zinc becomes (-)
- The conducting loop
provides a path for
the electrons to flow
from the Zinc to the
Copper
Dry Cells
- Same idea as a wet cell
but uses a paste instead
of an acid/salt solution
- Smaller
- Easier to handle/transport
Ways to Represent Circuits
- Words
- A circuit containing three light bulbs & 3 AA
batteries
- Picture
- Schematic
Component
Symbol
Alternate
Lamp
Light
Indicator
Switch
Open
Shut
Cell (1.5V)
Battery (9V)
Wire
Resistor
Schematic Diagram Practice
- Write & Switch -
Online PHET Lab
Measuring Electrical
Current
- How many charges
(electrons) past by a
given point per unit
time
- The coulomb is the unit
used when measuring
charge (C)
- 6.25 x 1018 electrons
Measuring Electrical
Current
Current = coulomb/second
- Also known as an
ampere (A)
- Commonly called amps
Measuring Electrical
Current
- Therefore, the formula
utilized is:
I = Q/t
- Where:
- I = electric current (A)
ampere
- Q = charge (C) coulomb
- t = time (usually seconds)
Math Breakdown
- List the given numbers (which variables do
you have)
- What variable is the question asking you to
find?
- Write down your formula
- Solve using algebra
- Remember units
Example One
- Given:
Q = 0.15C
t = 1s
- Calculate I
- What are the units for I?
Example Two
- A flashlight bulb has a
label that reads 0.25A.
- How many coulombs of
charge pass through the
bulb in 1 second?
Measuring Electrical
Potential
- Looks at the potential
difference between the
negative & positive
terminals
- The coulomb or joule is
the unit used when
measuring potential
- Called Volts
Measuring Electrical
Potential
- A Volt = the energy of
each charge
- If there is more charges,
there is more total
energy
- Energy = charge x
Electrical Potential
(volts)
Measuring Electrical
Current
- Therefore, the formula
utilized is:
V = E/Q
- Where:
- V = electric potential (V)
volts
- E = energy (J) joules
- Q = charge (Q) couloumbs
Example Three
- Given:
E = 86J
V = 9V
- Calculate Q:
Example Three
- How much energy can a
toaster produce when it
is plugged into a 110V
outlet with a total
charge of 25C passing
through?
Current, Voltage, Resistance Worksheet
Electrical
Devices
Used in a
Week
1
20
Essential
Vs
Extra
Hrs/Week
Rank from
“Uses Most”
to
“Uses Least”
- Conductors emit energy
in the form of heat or
light
- Due to resistance
- The “loss” of energy in
the form of heat creates
inefficiencies
- Bad = light bulbs
- Good = stove elements
- Power = how much energy is
used in a certain amount of time
- The formula utilized for energy
consumption (aka Power) is:
P=IxV
- Where:
- P = Power (Watts)
- I = Current (Amps)
- V = Voltage (Volts)
Example One
- How much current does
a 1500W hair dryer draw
when plugged into an
110V household plug in?
-P=IxV
Example Two
- How much power is
consumed by a 17 inch
LCD screen that draws
1A at 110V?
-P=IxV
Example Three
Consider the power rating of the following items:
Stove: 2000W
Light Bulb: 60W
CD Player: 25 W
Vacuum: 800 W
Toaster: 900 W
TV: 200W
Microwave: 650W
- A typical household circuit breaker is
designed to allow a maximum of 15A on a 110 V
circuit.
- How much power can the circuit handle?
Example Three (Cont)
Consider the power rating of the following items:
Stove: 2000W
Light Bulb: 60W
CD Player: 25 W
Vacuum: 800 W
Toaster: 900 W
TV: 200W
Microwave: 650W
- A typical household circuit breaker is
designed to allow a maximum of 15A on a 110 V
circuit.
- Determine if the breaker will trip if the toaster
and microwave are both being used on the
same circuit.
Example Three (Cont.)
Consider the power rating of the following items:
Stove: 2000W
Light Bulb: 60W
CD Player: 25 W
Vacuum: 800 W
Toaster: 900 W
TV: 200W
Microwave: 650W
- A typical household circuit breaker is
designed to allow a maximum of 15A on a 110 V
circuit.
- Determine if the breaker will trip if the
vacuum, TV, and microwave are on.
Example Three (Cont.)
Consider the power rating of the following items:
Stove: 2000W
Light Bulb: 60W
CD Player: 25 W
Vacuum: 800 W
Toaster: 900 W
TV: 200W
Microwave: 650W
- A typical household circuit breaker is
designed to allow a maximum of 15A on a 110 V
circuit.
- Can the stove be used on this circuit?
Example Four
- Would a stove that
requires 2000W work on
a 30A with 220V circuit?
-P=IxV
Example Five
- You have a 1500W hair dryer.
- How many kilowatts (kW) would the hair dryer use?
- 1.5kW
- By the end of a 30 day month how many hours will it
have been used if it is used for 3 minutes each day?
- 90 mins or 1.5 hours
- If it costs $0.15 to use 1 kW for an hour. How much
would it cost to operate the hair dryer for a month at
3 minutes each day. (Total = cost x kW x hrs)
Understanding Energuide. (2013). Uploaded by the Office of Climate Change.
Available online at: http://www.turnbackthetide.ca/athome/appliances/energuide.shtml#.U3IdU_ldWSo