Transcript Conservation of Electric Charges

Monday January 23, 2012
Warm Up
Electrons have a
a. Positive charge and
protons have a negative
charge
b. Negative charge and
protons have a positive
charge
c. Neutral charge
d. Negative charge and
protons have a neutral
charge
Classwork:
#17 Simple Mach Quiz
#18 Quiz Corrections
#19 Intro to Electricity
Lecture Notes
#20 Vocab practice
Homework:
#20 Vocab Practice
#18 Quiz Corrections
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How does an atom become electrically
charged?
When an atom gains or loses an electron
What is Electricity?
Like charges repel and opposite charges attract
• Electric Charge – like charges repel and unlike
charges attract
– Created through loosing or gaining electrons
– An atom that gains an electron is negatively
charges
– An atom that looses an electron is positively
charged
How do you create a charge?
• Atoms are typically neutral charge,
but they can become charged in 3
ways
– Friction – electrons are wiped from
one object to another through rubbing
surfaces
– Conduction – electrons move from 1
object to another through direct
contact
– Induction - charges in uncharged metal
are rearranged without touching
Conservation of Electric Charges – electrons are not lost or
created , they just move from 1 atom to another
Moving Charges
• Electrical Conductors – material where
charges move easily
• Electrical insulator – material where charges
cannot move easily
• Static electricity – charges at rest on an
object
• Electric discharge – loss of static electricity as
charges move off an object
• Lightening is an example of moving charges
Lightening
is an
example of
attracting
electrical
charges
#20 Vocab Practice
Tuesday January 24, 2012
Warm Up
Which of the following
statements is correct?
a. Like charges attract and
unlike charges repel
b. Unlike charges attract
and like charges repel
c. Unlike and like charges
attract
d. Unlike and like charges
repel
Classwork:
#21 Current Notes
#22 Intro to Electricity
Review
Homework:
Complete # 22
• Electrical current – the rate that charges pass a given point
• When you turn on a switch you command electrons to
move forward instantly
• Measured in amperes or AMPS
• There are 2 kinds of current: AC & DC
• AC -alternating current, electrons can move in both
directions
• EX: your house electricity
• DC – direct current, electrons travel in same direction
only
• EX: batteries
• Electrons want to move forward because of voltage – the
amount of energy required to move electrons forward
• More voltage = higher current
• Resistance – opposition to current flowing
• Insulators have high resistance
Wednesday January 25, 2012
Warm Up
Which of the following
materials serve as an
insulator?
a.
b.
c.
d.
Copper
Iron
Aluminum
rubber
Classwork:
#23 Circuit Prediction
Guide
#24 Magic School Bus
Gets Charged
#23 Prediction Guide
Divide you paper in half
Prediction Before Video
Draw what you think a circuit looks like
What do you think the main parts of a
circuit are?
Why do you think light switches are
important?
After Video
#24 Magic School BUS Gets Charged
#23 Prediction Guide
Fill in the other side of your prediction
guide!
Prediction Before Video
Draw what you think a circuit looks like
What do you think the main parts of a
circuit are?
Why do you think light switches are
important?
After Video
Thursday January 2, 2012
Warm Up
Classwork:
In which type of current
to charged particles
flow in only one
direction?
#25 READ & Section
Review pg 499 #1-5 & 7
a.
b.
c.
d.
AC
DC
Voltage
Amperes
Friday January 27, 2012
Warm Up
Which of the following
describes the method of
creating a charge by
wiping electrons from one
object onto another?
a.
b.
c.
d.
Conduction
Convection
Induction
Friction
Classwork:
#27 Circuit Notes
#28 Circuit Practice
Homework:
None
#27 Circuit Notes
• Electric circuits – complete closed path
through which electric charges flow
• All circuits have 3 basic parts – load, energy
source & wires
– Load – radio, fan, transforms electrical energy into
another energy
– Energy source – outlets, batteries
– Also have switch – used to open or close circuit
• Series circuit – all parts are
connected in a single loop
• Only 1 path for electricity to
flow
• Adding more bulbs will reduce
the brightness of each bulb
• If any lightbulb goes out or
turns off none of the others
would work
• Parallel circuit – loads are
connected side by side
• Electricity branches off to each
bulb
– Keeps brightness the same
no matter how many bulbs
• Benefit – that each load can
work individually of others
Circuit Safety
• If wires get frayed It can cause the resistance
to increase, and the circuit can heat up and
fail
• If a circuit has too many loads it can also
overheat (possible fire!)
• Fuses & circuit breakers have thin metal strips
that melt and break the circuit if over heated
1. Describe some disadvantages to using a
series circuit.
2. Draw a series circuit with 3 different loads
on it.
3. Will the series circuit that you drew work
well? Why or Why Not?
4. Draw a parallel circuit with the same 3 loads
in it.
5. Why would the parallel circuit you drew
work better than the series circuit