Download Electricity Notes - Lanier Bureau of Investigation

Electricity Notes
Electrical charge and static electricity
Atoms are made of charges, protons (+) and
electrons (-). These charges exert forces.
They push (repel) and pull (attract)).
Law of electrical charges: like charges repel
(push apart) and unlike charges attract (pull
toward each other).
http://www.youtube.com/watch?v=Y5LxwZCfW4
Electric field is the location around ONE
charge that would affect another charge
within it.
Electric force is the push or pull between
two charges.
The amount of the force is based on the
size of the charges and the distance.
(1) ATTRACT OR (2) REPEL
a. Two positive charges
b. Two negative charges
c. A negative and a positive charge
d. +
e. +
+
f. -
Charge it!
Atoms usually are neutral (no charge) because
they have an equal number of protons and
electrons which cancel each other out.
However, atoms can lose electrons and become
positively charged. (Only electrons move, not
protons or neutrons)
a.
b.
c.
d.
e.
Electric field
Electric force
Neutral charge
Positive charge
Negative charge
3
2.
1
5.
4
How to charge an object
There are three ways to charge an object.
1) Friction – rubbing two things together results
in electrons moving from one object to the
other.
2) Conduction – transfer of electrons by touch
(similar to thermal conduction)
3) Induction – a negatively charged object
approaches a neutral object making all the
negative particles push away
http://phet.colorado.edu/simulations/sims.php?sim=Balloons_and_St
atic_Electricity
How do we know something is
charged?
An electroscope shows whether something is
charged by drawing the same charges from
the metal and making the metal leaves spread
apart.
(1) Conduction (2) Friction (3)
Induction
A
Charging an object by
rubbing it against
another object so that
electrons move from
one to the other
C
B
Charging an object by
touching to another
object so that electrons
transfer.
Bringing a charged object
near an uncharged object
so that the like charges are
repelled and the uncharged
object becomes charged.
(1) Conduction (2) Friction (3)
Induction
A
B
C
Moving charges
Some materials conduct electricity meaning
they allow charges to move easily through
them, these are called conductors.
- Conductors are used for wires.
- Water is a conductor (unless it is distilled)
- We also have to guard against materials that
will allow electricity to flow through them if it
isn’t something we want.
Insulators are materials in which charges cannot
easily move. Such as:
- Plastic
- Rubber
- Wood
- Glass
- Air
(1) Conductor or (2) Insulator
1)
2)
3)
4)
5)
6)
7)
Plastic water bottle
Metal hinge
Basketball
Lead
Stapler
Wooden pencil
Paper airplane
(1) Conductor or (2) Insulator
A
B
c
D
E
Static Electricity
Static electricity is the buildup of charges on an
object. It is called static because it is not
moving.
Electric discharge – eventually static electricity
leaves an object. We call this electric
discharge. It can occur slowly or quickly, as in
electrical shock.
http://phet.colorado.edu/simulations/sims.php?sim=John_Travo
ltage
A cell is a device that produces an electric
current by converting chemical energy into
electrical energy. A battery is made of several
cells. Batteries use DC or direct current which
moves in one direction.
Photocells is the part of a solar panel that
converts light into electrical energy.
A.
B.
C.
D.
Static electricity
Electrical discharge
Cell
Photocell
1. Converts chemical energy into electrical energy
2. Electric shock- when charges leave one object for
another less charged object
3. The build up of charges on an object
4. Converts light energy into electrical energy
Electric current
Current is the rate at which charges pass a
certain point.
Our homes use AC or alternating current where
the charges continually switch from one
direction to the other. Voltage may vary. In
the US we use 120V
Resistance
Resistance is the opposition to the flow of
electrical charge. It is a type of “electrical
friction“.
RESULTS IN HEAT!
A. Electric current
B. Static electricity
C. Resistance
1. The result when charges build up but do not
move.
2. The result when charges are opposed (slow
down)
3. The result when charges move pass a certain
point