Transcript So, now onto the review……

The Physics of
Electricity and
Magnetism
Welcome
Back and
a Quick
Electricity
Review
9-12 Science Std: Phys 5e, i, j, m
First, a quick look at the schedule
Mon
Tue
Wed
Thu
Fri
1/12
1/13
1/14
1/15
1/16
Welcome
Back and a
Quick Review
Magnets
making
electricity
Activity –
Making
electricity with
a magnet and
measuring it
Entropy or
how to
measure
disorder
End ofA ll of
Physics
Topics Review
and select
project topics
1/19
1/20
1/21
1/22
1/23
End of
Physics
Project Work
End of
Physics
Project Work
End of
Physics
Project work
and select
presentation
order
Physics
Project
Presentation
Groups 1, 2, 3
Martin Luther
King Jr’s
Birthday
NoS chool
First, a quick look at the schedule
Mon
Tue
Wed
Thu
Fri
1/26
1/27
1/28
1/29
1/30
Physics Exam
Make up
Physics Exam
and
Exam Review
Physics
Project
Presentation
Groups 4, 5, 6
Physics
End of
Project
Physics Exam
Presentation
Review
Groups 7, 8, 9
2/2
2/3
2/4
2/5
2/6
Final Exam
Review Geology
Final Exam
Review Physics
Final Exams
(short day)
Periods 1, 4
Final Exams
(short day)
Periods 2, 5
Final Exams
(short day)
Periods 3, 6
First, a quick look at the schedule
So, here are the important dates for you……
•Present Physics Projects:
•1/23, 1/26, 1/27 (Fri, Mon, Tue)
•Physics Exam Review
•1/28 (Wed)
•End of Physics Exam
•1/29 (Thu) Makeup 1/30 (Fri)
•Final Exam Review
•2/2-2/3 (Mon-Tue)
•Final Exams
•2/4-2/6 (Wed-Fri) Depending on the period
So, now onto the review……
We focused on the Electrostatic Forces
We started with the atom…
The atom has a positively
charged nucleus
and negatively charged
electrons going around the atom
The positively charged protons and the
negatively charged electrons attract each other
As long as the atom has a equal number of protons
and electrons, the electrical charge is balanced and
there are no electrostatic forces
So, now onto the review……
We learned what happens to the atom….
If an electron leaves the atom
The atom’s electrical
charge is unbalanced
The atom has a positive
charge
And the negatively charged electrons are
floating around by themselves
This makes free negatively charged electrons
and positively charged ions
So, now onto the review……
The electrons can get pulled away for many reasons…..
They can get rubbed off….
Like when we rub a balloon
against our hair
Or when we used the Van
De Graff Generator
So, now onto the review……
The electrons can get pulled away for many reasons…..
Or they can be forced off….
By having a large electric
potential from a battery…
Or from some other
electrical power source
So, now onto the review……
But once away, electrostatic forces work on them….
Charges that are the same repel each other
Opposite charges attract each other
So, now onto the review……
But once away, electrostatic forces work on them….
The amount of force attracting or repelling depends on
The amount of charge…..
The bigger the charge….
The bigger the force between them
More Charge = More Force
So, now onto the review……
But once away, electrostatic forces work on them….
The amount of force attracting or repelling depends on
The distance between the charges
The closer the charges…
The bigger the force between them
Closer Together = More Force
This is a much bigger effect than changing the sizes
of the charges
So, now onto the review……
These charges create fields of force around them
Not that kind of force field……….
So, now onto the review……
These charges create fields of force around them
Every thing that has an electric charge puts out
lines of force that attract or repel other charges
A point charge puts
out lines in all
directions
So, now onto the review……
These charges create fields of force around them
Every thing that has an electric charge puts out
lines of force that attract or repel other charges
A plate charged
source puts out
lines of force in one
direction
The lines of force coming
from the point or the plate
are called Vector Fields
So, now onto the review……
We can measure the amount of force
This force is called the electric potential
Or electric voltage
The higher the voltage,
the higher the potential
It is like a ball rolling
down a hill….
A small hill won’t make
the ball roll fast
So, now onto the review……
We can measure the amount of force
This force is called the electric potential
Or electric voltage
The higher the voltage,
the higher the potential
It is like a ball rolling
down a hill….
But a big hill will really
get a ball rolling…
So, now onto the review……
But the voltage is just the driving force
What makes things happen is
the moving charged electrons
When charges move, we can
measure it another way
The moving charged particles
is called the electrical current
So it isn’t the voltage that hurts
us, it is the current that we feel
So, now onto the review……
Then, we covered the 4th state of matter….
If you remember, things come
4 different ways….
Liquid
Solid
Gas
So, now onto the review……
Then, we covered the 4th state of matter….
If you remember, things come
4 different ways….
and Plasma
So, now onto the review……
Plasma is a special condition
It is where you have lots of ions and electrons
all floating around together all the time
Because they are all mixed up, the positive
and negative charge forces cancel each other
But because the ions and
electrons are all floating
around free, plasma can
easily conduct electricity
So, now onto the review……
Electrical current can make a magnetic field
When an electrical current runs
through a wire it creates a
magnetic field
You can see the field
here using iron filings
sprinkled around a wire
So, now onto the review……
Electrical current can make a magnetic field
The shape of the magnetic field
is a circle around the wire
The direction of the magnetic
field is shown using the right
hand rule
Wrap your hand around the
wire with your thumb pointing
in the direction of the current
and your fingers show the
field’s direction
So, that is what we have covered
What you should remember is……
Charged particles are sources of electric fields
Charged particles feel forces from the electric fields
of other charges
Electric fields contain energy
Electric fields work in a specific direction (they are
vector fields)
Electric forces get bigger as the amount of charge
gets bigger
Electric forces get bigger as two charges get closer
to each other and has a bigger effect than changing
the size of the charges
So, that is what we have covered
What you should remember is……
Static electric fields are caused by groups of
electric charges sitting in one place
Plasma is made up of ions and free electrons
Plasma can conduct electricity
Electric current in a wire makes a magnetic field
The direction of the magnetic field is shown by
the right hand rule
Now that we have finished
We can finish magnetism and electricity
And how magnetism affects electricity
And then finally how we
can measure how much
order is in a system
But that is for later…….