Notes: Electricity
What is it?
Natural forces created by the flow of electrons. A movement of matter not energy
2 forms:
Current: Flowing electrons moving from
one atom to another through a conductor
Static: A electric charge at rest
Charges of Atoms
Negative (-)
(Extra electrons)
Positive (+)
neutral
( Missing Electrons)
3 ways atoms can get charged
Friction
Transfer of free
electrons when neutral
objects are rubbed
together
Conduction
Transfer of free
electrons a charged
object comes in contact
with a neutral object
thus charging it
What is this? ELECTROSCOPE
Induction
Transfer of free
electrons when a
conductor be becomes
charged when placed
near but not touching a
charge object
What does it do?
Piece of equipment used to determine if an
object that touched it has a charge.
Explain how it works
When a charged body is brought near the top metal knob, the charge travels down
the wire then both strips at the bottom acquire a like charge (that is, they both
become negative or both become positive). As a result, they repel each other and
spread apart to form “V”
Static Electricity
Ex. Shock from door knob
(4 facts)
-Proven by Ben Franklin
-Static electricity will be worse on a dry non-humid day.
-Form when we accumulate extra electrons
-The only form of electricity I the 18th century
Electric Discharge
What is it?
Loss off static electricity
as charges move thru
an object.
Ex. Lightning
The Law of Electric Charges
Positive and positive repel
The closer the charges are to each other the greater
the force is created
Negative and Negative repel
Positive and negative attract
Label the
Electric Current
What is it? Moving electrical charges
What are the 2 types?
Direct (DC) : flow only one way ex. battery
Alternating (AC); charges change direction ex outlet
How do electrons flow?
From negative to positive
Parts required? Power source, wire, load
Extra part? switch
A circuit is a path along which
electrons move.
Open Circuit ( incomplete)
2 Types of Circuits
Series
current is not flowing
Switch is open (off)
Parallel
Closed Circuit (complete)
Current is flowing
Switch is closed ( on)
-
row
1. Loads are in a ________
.
2. There is only _______
path
1
for the current to follow.
3. Loads __________
the
share
the current .
4. A gap in the current will
all
make ______
the loads
Inoperable.
5. ______
good for the wiring
Not
of a house
row
1. Loads are not in a _________.
2. There are several paths for
the current to follow.
3. Each load gets the maximum
sharing
current. No ______________
4. A gap in the current only
one
makes ______
load inoperable.
5. Excellent
__________ for the wiring of
a house.
Ohms Law:
Current= Voltage
Resistance
Matching
Slows down current
Potential Energy
Voltage
Current
Resistance
Flow of electrons
Amps (I---intensity)
Volts (E or V)
Shorts
Excessive current
flow due to water
or broken wires.
Wires heat up &
burn.
Fuses
Thin strip of metal that
heats up and melts
with excessive current
flow. Prevents a short
by stopping flow.
Circuit Breakers
Switch that opens
automatically with
excessive current flow .
Prevents a short by
stopping flow.
.
Wires heat up & burn
Ohms (R)
If voltage increases, current increases
& resistance stays the same.
If resistance increases, current decreases
& the voltage stays the same.