Transcript Intro to Electricity

Lets begin with some questions.
1) What is electricity made of?
2) How are static electricity and the electricity
found in our homes similar and different?
3) What is electricity's relationship with
magnetism?
Static Electricity and Charges
Magnets, Static Electricity,
Electricity, OH MY!!
• You are all familiar with magnets, static
electricity, and electricity. However did you
know that all three are related to one another?
• All three (magnets, static electricity, and
electricity) are the result of a single property
of matter...electric charge.
Atoms
• The electron is negatively charged.
• The proton is positively charged.
• The neutron has no charge, it is neutral.
Charge
• Most things have the same number of electrons
and protons in them, and they don’t have any
overall charge.
• If this isn’t true though interesting things can
happen.
Changing Charge
• How can we change a charge of an object?
– In order to change a charge we need to have
electrons move away from their atom they were
attached to.
– This can be done a number of ways. One of the
simplest is by rubbing two objects together.
Charge
Lets imagine that we have an object that is
filled with atoms. Well some of these atoms
can have different “charges” based on the
number of positive and negative atoms the
object will have a positive, negative, or neutral
charge.
We will draw atoms, just "+" and "–" to
illustrate the overall charges
Charge
We will draw atoms, just "+" and "–" to
illustrate the overall charges
e.g. a neutral object
5+
5overall charge 0
Charge
We will draw atoms, just "+" and "–" to
illustrate the overall charges
e.g. a positive object
5+
3overall charge 2+
Charge
We will draw atoms, just "+" and "–" to
illustrate the overall charges
e.g. a negative object
5+
8overall charge 3 -
What is Static Electricity?
Static Electricity: an imbalance of electric
charge on the surface of an object.
• Static electricity is caused when certain
materials are rubbed against each other.
• Electrons can be rubbed off one material and on
to another.
• The material that has got extra electrons is now
negatively charged
• The material which has lost electrons is
positively charged.
What is Static Electricity?
Law of Electric Charges:
What is Static Electricity?
Law of Electric Charges:
1. Opposite charges attract
What is Static Electricity?
Law of Electric Charges:
1. Opposite charges attract
2. Like charges repel
What is Static Electricity?
Law of Electric Charges:
1. Opposite charges attract
2. Like charges repel
3. Charged objects attract neutral objects
Why not static electricity?
• If static electricity and electrical current are the
same thing (electrons), why don’t we use it as
a power source?
– Static electricity is not stable enough to be a
continuous or regular source of energy.
Gaining Charge
• How does a piece of matter become charged?
– What does a neutral charged atom look like?
– What does a positively charged atom look like?
– What does a negatively charged atom look like?
Potential and Kinetic Energy
Remember all forms of energy have kinetic and
potential energy.
Analogy
The electric field is the space
around an electrical charge
just like
a gravitational field is the space
around a mass.
Electric Field
• Space around a charge.
What is the difference?
Electric Field Lines
Electric Field Lines of two Positive
Charges
Electric Field Lines
• Lines that indicate the strength and
direction of the electric field.
• The more dense the lines, the stronger the
field.
Which field is stronger?
• A
B
Electrical Potential
• Electricity has potential:
– This energy comes from the charge particle has
due to its position in an electric field.
– Because like charges repel, it takes energy to push
a charged particle closer to another particle with a
like charge. That energy is stored as the electric
potential energy. These particles can move and
want to/will when it is free to move.