Electricity and Magnetism

1. Electricity & Magnetism
Static, Currents, Circuits
Magnetic Fields & Electro Magnets
Motors & Generators

2. Atoms…
 Have neutrons, protons, and
electrons.
 Protons are positively charged
 Electrons are negatively charged

3. 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.

4. +
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+
+
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The world is filled with electrical
charges:
+
+
+
+
+
-
-
- -
-
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- --

5. What is this electrical potential
called?
 Static Electricity
- -
-
-
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++
+
+

6. 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.

7. 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)

8. Electricity that moves…
 Current: The flow of electrons
from one place to another.
 Measured in amperes (amps)
 Kinetic energy

9. How can we control currents?
 With circuits.
 Circuit: is a path for the flow of
electrons. We use wires.

10. There are 2 types of currents:
 Direct Current (DC) – Where
electrons flow in the same
direction in a wire.

11. There are 2 types of currents:
 Alternating Current (AC) –
electrons flow in different
directions in a wire

12. http://www.youtube.com/wa
tch?v=HqMqdFNWX4s#t=2
37

13. 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.

14. Series Circuit

15. http://www.youtube.com/watch?
v=u-
7k8wpl_ZU&list=PLAO5cUCypo
9w-cFeJc2QGqVW0n4ZV42Q1

16. 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.

17. Parallel Circuit

18. http://www.youtube.com/watch?
v=MxH7hnuBfC4&list=PLAO5c
UCypo9w-
cFeJc2QGqVW0n4ZV42Q1

21. Conductors vs. Insulators
 Conductors – material through
which electric current flows easily.
 Insulators – materials through
which electric current cannot
move.

22. Examples
 Conductors:
Metal
Water
 Insulators:
Styrofoam
Rubber
Plastic
Paper

23. 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.

24. 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

25. 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.

26. Difference b/t Volts and Amps
 Example – you could say that…
Amps measure how much water
comes out of a hose.
Volts measure how hard the water
comes out of a hose.

27. Ohm’s Law
 Resistance = Voltage / Current
 Ohms = Volts / Amps

28. Practice with Ohm’s Law
Ohms Volts Amps
4 100 25
15 150 10
2 30 15
9 45 5
6 48 8

29. What is an electromagnet?
 Electromagnet – a magnet made
from a current bearing coil of wire
wrapped around an iron or steel
core.

30.  http://www.youtube.com/watch?v=iSuSWi7YThA

31. 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.

32.  http://www.youtube.com/watch?v=NqdOyxJZj0U
#aid=P89ox56462A

33. What is a motor?
 Motor – a device that changes
electrical energy to mechanical
energy that can do work.

34. That’s It !!!!