Electricity & Magnetism
Static, Currents, Circuits
Magnetic Fields & Electro Magnets
Motors & Generators
Atoms…
Have
neutrons, protons
neutrons,
protons,, and
electrons..
electrons
Protons are positively charged
Electrons are negatively charged
Electrons…
Are
located on the outer edges of
atoms…they can be moved
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::
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
energy
stored..
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
moves…
…
Current
Current::
The flow of electrons
from one place to another.
Measured in amperes (amps)
Kinetic energy
How can we control currents?
With
circuits.
circuits.
Circuit
Circuit:: is a path for the flow of
electrons. We use wires
wires..
There are 2 types of currents:
Direct
Current (DC) – Where
electrons flow in the same
direction in a wire.
There are 2 types of currents:
Alternating
Current (AC) –
electrons flow in different
directions in a wire
There are 2 types of circuits:
Series
Circuit:: the components
Circuit
are lined up along one path. If
the circuit is broken, all
components turn off.
Series Circuit
There are 2 types of circuits:
Parallel
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.
off.
Parallel Circuit
Conductors vs. Insulators
Conductors
– material through
which electric current flows easily
easily..
Insulators
– materials through
which electric current cannot
move..
move
Examples
Conductors
Conductors::
Insulators
Insulators::
Metal
Styrofoam
Water
Rubber
Plastic
Paper
What is Resistance?
The
opposition to the flow of an
electric current, producing heat
heat..
The greater the resistance, the
less current gets through.
Good conductors have low
resistance.
Measured in ohms.
What Influences Resistance?
Material
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
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?
Electromagnet
– a magnet made
from a current bearing coil of wire
wrapped around an iron or steel
core.
What is a generator?
Generator
– a machine that
changes mechanical energy to
electrical energy
Usually use moving magnets to
create currents in coils of wire.
What is a motor?
Motor
– a device that changes
electrical energy to mechanical
energy that can do work
work..
That’s It !!!!