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Transcript
Electricity & Magnetism
Static, Currents, Circuits
Magnetic Fields & Electro Magnets
Motors & Generators
Atoms…
 Have
neutrons, protons, and
electrons.
 Protons are positively charged
 Electrons are negatively charged
Electrons…
 Are
located on the outer edges of
atoms…they can be moved.
 A concentration of electrons in an
atom creates a net negative
charge.
 If electrons are stripped away, the
atom becomes positively charged.
The world is filled with electrical
charges:
+
-
+ +
+
+ +
+
+
+
+
-
What is this electrical potential
called?
 Static
-
Electricity
-
- -
+
++
++
Static Electricity
 The
build up of an electric charge
on the surface of an object.
 The charge builds up but does not
flow.
 Static electricity is potential
energy. It does not move. It is
stored.
Static Discharge…
 Occurs
when there is a loss of
static electricity due to three
possible things:
Friction
- rubbing
Conduction – direct contact
Induction – through an electrical
field (not direct contact)
Electricity that moves…
 Current:
The flow of electrons
from one place to another.
 Measured in amperes (amps)
 Kinetic energy
How can we control currents?
 With
circuits.
 Circuit: is a path for the flow of
electrons. We use wires.
There are 2 types of currents:
Current (DC) – Where
electrons flow in the same
direction in a wire.
 Direct
There are 2 types of currents:
Current (AC) –
electrons flow in different
directions in a wire
 Alternating
http://www.youtube.com/wa
tch?v=HqMqdFNWX4s#t=2
37
There are 2 types of circuits:
 Series
Circuit: the components
are lined up along one path. If
the circuit is broken, all
components turn off.
Series Circuit
http://www.youtube.com/watch?
v=u7k8wpl_ZU&list=PLAO5cUCypo
9w-cFeJc2QGqVW0n4ZV42Q1
There are 2 types of circuits:
Circuit – there are several
branching paths to the
components. If the circuit is
broken at any one branch, only
the components on that branch
will turn off.
 Parallel
Parallel Circuit
http://www.youtube.com/watch?
v=MxH7hnuBfC4&list=PLAO5c
UCypo9wcFeJc2QGqVW0n4ZV42Q1
Conductors vs. Insulators
– material through
which electric current flows easily.
 Conductors
– materials through
which electric current cannot
move.
 Insulators
Examples
 Conductors:
 Insulators:
 Metal
 Styrofoam
 Water
 Rubber
 Plastic
 Paper
What is Resistance?
 The
opposition to the flow of an
electric current, producing heat.
 The greater the resistance, the
less current gets through.
 Good conductors have low
resistance.
 Measured in ohms.
What Influences Resistance?
of wire – aluminum and
copper have low resistance
 Thickness – the thicker the wire the
lower the resistance
 Length – shorter wire has lower
resistance
 Temperature – lower temperature has
lower resistance
 Material
What is Voltage?
 The
measure of energy given to
the charge flowing in a circuit.
 The greater the voltage, the
greater the force or “pressure”
that drives the charge through the
circuit.
Difference b/t Volts and Amps
 Example
 Amps
– you could say that…
measure how much water
comes out of a hose.
 Volts measure how hard the water
comes out of a hose.
Ohm’s Law
 Resistance
 Ohms
= Voltage / Current
= Volts / Amps
Practice with Ohm’s Law
Ohms
4
15
2
9
6
Volts
100
150
30
45
48
Amps
25
10
15
5
8
What is an electromagnet?
– a magnet made
from a current bearing coil of wire
wrapped around an iron or steel
core.
 Electromagnet

http://www.youtube.com/watch?v=iSuSWi7YThA
What is a generator?
– a machine that
changes mechanical energy to
electrical energy
 Usually use moving magnets to
create currents in coils of wire.
 Generator

http://www.youtube.com/watch?v=NqdOyxJZj0U
#aid=P89ox56462A
What is a motor?
– a device that changes
electrical energy to mechanical
energy that can do work.
 Motor
That’s It !!!!