1

First (Electric charge)
1) The matter consists of atoms which consist of
electrons of negative charge , protons of
positive charge ,neutrons that are neutral ,
nucleus that is positive
2) law of electric charges: states that
like charges repel and opposite charges
attract
;so the electrons attract to protons and
then electrons couldn't be held in atoms
2
3) Electric force:
the force of attraction or repulsion on a charged
particle that is due to an electric field
; And it depends on:
i) the amount of the electric charge where the
greater the charge is, the greater the force
ii) the distance between the charges where the
closer the charges are to each other, the
greater the force is
4) Electric field:
the space around a charged object in which another
charged object experiences an electric force
3
Second (Charge it)
1) We noted that nothing that the number of
electrons = the number of protons and they
cancel each other ; So

How can anything made of atoms be charged?
An object becomes positive charged when it
loses electrons
and it becomes negative charged when it gains
electrons
and the objects can become charged by
friction, conduction and induction
2) An electrons move from one atom to another ,
which makes areas that have different charges ;
Then because of the charges aren't created or
destroyed , the charges are said to be conserved
4
2) Friction:
It happens when an electrons are wiped
from one object onto another
3) Conduction:
It happens when an electrons move
from one object to another by direct
contact
4) Induction:
It happens when charges in an
uncharged metal object are
rearranged without direct contact with
a charged object
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6
Third (Detection charge)
An electroscope:
A device that is used to see if something is
charged
Its structure:
1) a glass flask that has a metal rod in its
rubber stopper
2) two metal leaves are attached to the
bottom of the rod
3) when the device isn't charged ; the leaves
hang straight line
4) when the device is charged, the leaves
repel each other
5) when the ruler touches the top of the
metal , the electrons move from the ruler
to the metal

7

Fourth (Moving Charges)
Electrical conductor:
a material in which charges
can move freely
Electrical insulator:
a material in which charges
cannot freely move
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
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Fifth (Static Electricity) or ( Not moving Electricity)
Static electricity: electric charge at rest
Generally the charges of static electricity don't move
away from the object that they are in
So the static electricity produced by friction or
induction
Electric discharge: the release of electricity stored in
a source
For example : lightening and the spark when you
reach out for a doorknob after walking across a
carpet and the clothes tumbling in dryer
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
First (Electric Current)
Electrical energy:
the energy of electric charges


So, the electric charges flow through wires
Electric current:
the rate at which charges pass through a given point;
measured in amperes


The electric field causes the free electrons in the wire
to move
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
The kinds of electric current :
1) Direct current (DC):
Charges in direct current move in only one direction
2) Alternating current (AC):
Charges in an alternating current reverse direction
many times a second
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
Second (Voltage)
Voltage:
the potential difference between two points;
measured in volts




Voltage is a measure of how much work is
The voltage needed to move a charge between two
points
If the voltage increases , the electric current will
increase
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Third (Resistance)
The opposition presented to the current by a
material or device




If the thickness of wire increases , the resistance
will decrease , because there are more spaces for
charges to flow
If the length of wire increases , the resistance will
increase , because there are few spaces for
charges to flow
If the temperature increases , the resistance will
increase , because there are vibrations of atoms
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
A good conductor as copper that has low R

A poor conductor as
iron that has high R
Super conductor:
A material of 0 ohm when the material is cooled at
a very low temperature

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
Fourth (Generating Electrical Energy)
1) The cell
Definition:
a device that produces an electric current by converting
chemical or radiant energy into electrical energy
Parts of a cell:
Electrolyte(mixture of chemicals): allow charges to flow
Pair of electrodes: the part of a cell through which
charges enter or exit
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Kinds of a cell:
a) Wet cell: it has a liquid as electrolyte as sulfuric
EX: Battery
b) Dry cell: it has a solid as electrolyte
EX: Flash lights
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2) The thermocouples
Definition:
A device that converts thermal energy into
electrical energy
Parts of a cell:
a) Joining wires of two different metals in a loop
b) The temperature difference with in the loop
causes charges to flow through the loop
c) More temperature difference leads to more
electricity
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3) The photo cell
Definition:
A device that converts light energy into electrical
energy
How it works:
The electrons gain the light energy and this energy
is converted into electrical energy
Example:
A dark strip in a calculator
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Introduction
Inside the electricity
V: Voltage ; I: Electric Current
P: Power
; E: Electrical Energy
; R: Resistance
; t: time
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1) Ohm’s law:
V=IXR
where
V: volt (V) , I: ampere (A) , R: ohm (Ω)
At constant V, R increases with decreasing of I
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2) Electric Power :
The rate at which electrical energy is converted into
other forms of energy
P=IXV
where
V: volt (V) , I: ampere (A) , P: watt (W)
Note:
P measures how the lamp make a brightness
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3) Electrical Energy :
It depends on the power of the electrical devices in
the house and the length of time that those
devices are on
E=PXt
where
E: Kilo Watt.hour (kWh) , t: time (s) , P: watt (W)
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4) How to save energy
By replacing items that have high power ratings
with items that have low power ratings
Examples:
Replace A.C with the fan
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
First (Parts of electrical circuits)
Definition:
A complete , closed path though which electric
charges flow
Its parts: 1) Energy source: can be a battery , a photo
cell, a thermocouple
2) wires: connect the parts of circuits; they
are made of conducting materials
that have low resistance as a copper
3) loads: change electrical energy to another
forms of energy ; as radio and bulbs
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4) switch: uses to open and close the circuit where
when the switch is opening that means
the circuit is turning off circuit
when the switch is closing that means the
circuit is turning on circuit
Switch is made of two pieces of
conducting material, one of which can be
moved
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
Second (Types of circuits)
Series circuits
Parallel circuits
A circuit in which the parts are joined
one after another such that the current
in each part is the same
A circuit in which the parts are joined
in branches such that the potential
difference across each part is the same
All loads have the same current
All loads have the same voltage
So , light glows with the same
brightness
So, every bulb uses the full voltage
from the battery that leads to the light
glows with a full brightness
But if you add a light bulb,
the brightness will decrease
They use in wiring burglar alarms
where if any part in this circuit fails ,
the circuit will fail
But if you add a light bulb,
the brightness will still the same
As in your home
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Third (Household circuit safety)
1) Circuit failure:


Causes from:
Broken wires or water can cause a
short circuits where in a short circuits
, there are many loads and the
current will increase

Results
: the wires get hot and a fire might
start and the circuit fails

Solutions : using a fuses and circuit breakers
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2) Fuses:
 It has a thin strip of metal

If the current is too high , the strip will melt and
the circuit will be opened
3) Circuit breakers:


It is a switch that automatically open if the
current is too high where a strip will warm, bend
and the circuit will be opened
For examples : A ground fault circuit interrupter
(GFCI)
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3) Electrical safety tips:
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CHAPTER 18
1. MAGNETS AND MAGNETISM
2. MAGNETISM AND ELECTRICITY
3. ELECTRICITY AND MAGNETISM
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
First (Magnet)
Any material that attracks iron or material
containing iron

Second (History)
More than 2000 years, the Greeks discovered a
mineral that was found in a part of Turkey called
Magnesia, the Greek called it Magnetite
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
Third (Magnetic properties)
Magnetic poles:
Any points on a magnet that have opposite magnetic
qualities
Be carful , the like poles are repelled but the opposite
poles are attracted
North and South:
if you attracts the magnet as a free form, we will note
the pole that points to the north is called the north and
the other pole is called south pole of magnet
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Magnetic force:
The force of attraction or repulsion generated by
moving or spinning electric charges
Be carful , the maximum force of the magnet is
found in the ends of the magnet
Magnetic field:
The region around a magnet in which magnetic
forces act
Magnetic fields lines:
The lines map out the magnetic field
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Fourth (The cause of magnetism)
All matters are made of atoms ; the electrons
move around the nucleus and this motion of
electrons is caused a magnetic field around the
matter
But, in some materials such as copper and
aluminum , the magnetic fields of individual
atoms cancel each other, then these materials
aren't magnetic materials
In the materials such as iron, nickel and cobalt
have a groups of atoms that are found in tiny
areas called domains which are arranged well and
in slightly one direction
The arrangement of domains inside the matter
leads to whether the material is magnetic or not
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Magnetic materials:
The materials that have a magnetic properties such
as iron, nickel, cobalt
Non-Magnetic materials:
The materials that haven't a magnetic properties
such as copper
How does the magnet lose its properties ?
1) hitting
2) dropping
3) increasing the temperature where the atoms
vibrate faster
4) putting a magnet in a strong magnetic field that
opposite its own field
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How can you make a magnet ?
By rubbing the magnetic material in one direction
with one pole of a magnet; as a result the domains
line up
What does happen if you cut the magnet ?
We note that each half will be a magnet
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Kinds of magnets
Temporary magnets:
Are easy to magnetize but lose their magnetization
easily
Such as: pure iron
Permanent magnets:
Are difficult to magnetize but retain their magnetic
properties for a long time
Such as: AL + NI
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
Earth as A magnet
1) William Gilbert suggested that
magnets point to the north because earth is one
giant magnet
2) Earth behaves as if it has a bar magnet running
through its center;
the poles of this imaginary magnet are magnet are
located near geographic poles of earth
3) If you put a compass on a bar magnet ,
the marked end of the needle points to the south
pole of the magnet
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4) That is because,
the compass needle points to the north because
the north pole of the earth is consider a magnetic
south pole
5) It is considered that
the earth has a giant magnet in its center and it has
a magnetic field from moving of earth that leads to
flow the liquid in its core and then the electric
charges move
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Aurora:
It is formed when charged particles from the sun
hit the oxygen and the nitrogen atoms in the air,
the atoms become excited and then give off light
of many colors
Aurora is seen near the north pole of the earth is
Northern lights or aurora borealis
Aurora is seen near the south pole of the earth
is southern lights or aurora australis
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First (Maglev (Magnetic Levitation) train)
The train in Japan that moves without touching the track
 Second (Discovery of electromagnetism)
A) Oersted putted the compass close to the wire, and he noted that:
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B) Oersted concluded that:
I.
II.
III.
IV.
an electric current produces a magnetic field
he also found that the direction of the
magnetic field depends on the direction of
electric field
Ampere did more research with electricity and
magnetism
the electromagnetism: the interaction between
electricity and magnetism
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
Third (How do you increase the magnetic field
strength ) ?
1) A solenoid
a coil of wire that carries electric current. An
electromagnet is a solenoid that has an iron coil
Its magnetic field increases with the increase of
number of loops and electric current
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2) Electromagnet:
a coil that has a soft iron core and that acts as a
magnet when electric current is in the coil
Notes:
1) the solenoid makes the domains inside the iron
line up and M.F of the electromagnet is the field
of solenoid + the field of the magnetized core
2) the field of electromagnet >>> that in solenoid
3) If there is an electric current inside the solenoid,
then it is on state
4) If there isn't an electric current inside the
solenoid, then it is off state
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
Fourth (Application)
1) Door bell:
It has two solenoids ( one to open lights and the
other to open sounds)
2) Galvanometer:
It has an electromagnet placed between the poles of
permanent magnet that is used to measure current
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3) Electric Motor:
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
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
First (History)
Oersted discovered that an electric current
produces a magnetic field
But, Henery discovered that a magnetic field
produces an electric current


Then, Faraday published the results of Henery
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
Second (Factors that affect an induced current)
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Third (Electromagnetic induction)
the process of creating a current in a circuit by
changing a magnetic field

Fourth (An electric current is made)
when a magnet moves in a coil of wire
or
when a wire moves between the poles of a magnet

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Fifth (Applications)
1) Electric generator:
A device that converts mechanical energy into
electrical energy
Its work:
It rotates a coil of wire through a magnet; this
motion produces an electric current

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2) Transformer:
A device that increases or decreases the voltage of
alternating current (N1/V1 = N2/V2)
Step –up transformers
Step –down transformers
Increase the voltage
Decrease the voltage
Decreases the current
Increases the current
Primary coil has fewer loops than
secondary coil
Secondary coil has fewer loops than
primary coil
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An alternating current:
The current that changes its direction
Its structure:
Sixth (Sources of electricity)
1)Thermal energy from nuclear power plants
2)Thermal energy from burning fuel power plants
3) Wind energy can turbines turbines that
produces electricity
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CHAPTER 20
1. NATURE OF WAVES
2. PROPERTIES OF WAVES
3. WAVE INTERACTIONS
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First (Introduction on a wave)
wave:
a periodic disturbance in a solid, liquid, or gas as
energy is transmitted through a medium
Energy transfers by a wave through a medium
Medium (media):
a substance in which a wave can travel
(solid, liquid, gas)
Most waves transfer energy by the vibration of
particles in a medium
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Second (Types of waves)
 Mechanical waves:
They need a medium to transverse
They consist of transverse and longitudinal waves

Electromagnetic waves:
They need a medium to transverse
They consist of transverse and longitudinal waves

Third (Combination waves)
When a waves at the boundary between two
media, transverse and longitudinal wave can
combine to form a surface wave

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Transverse waves
Longitudinal waves
a wave in which the particles of the
medium move perpendicularly to the
direction the wave is traveling
a wave in which the particles of the
medium vibrate parallel to the
direction of wave motion
Consist of
Crest (the highest point in a wave)
And
Trough (the lowest point in a wave)
Consist of
Compression
(a part of longitudinal wave where the
particles are crowded together
And
Rarefaction ((a part of longitudinal
wave where the particles are spread)
Ex: sea waves
Ex: sound waves
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First (Amplitude)
the maximum distance that the particles of a wave’s
medium vibrate from their rest position


Second (Frequency) (f)
the number of waves produced in a given amount of
time
And more wave length , leads to more energy
and its unit is Hertz (HZ)
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Third (Wave length) (λ)
the distance from any point on a wave to an
identical point on the next wave

More wave length , leads to less energy
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Fourth (speed of wave) (v)
the speed at which a wave travels through a
medium
v=fxλ

If the f increases , the λ will decrease at
constant v
So , The speed doesn't depend on f or λ
but depends on the properties of the
medium through which the wave travels
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First (Reflection)
the bouncing back of a ray of light, sound, or heat
when the ray hits a surface that it does not go
through

Echo: a reflected sound wave
Light wave reflecting off an object allow you to see
that object
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Second (Refraction)
the bending of a wave as the wave passes between two
substances in which the speed of the wave differs



When a wave moves from one medium to another, its speed
changes, then it will bend and travel in a new direction

Light is dispersed when passes through a droplet of water or
prism

when the light passes through a prism, it is divided into 7
colors because of the difference in wave length
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Third (Diffraction)
a change in the direction of a wave when the
wave finds an obstacle or an edge, such as an
opening

The increasing of λ leads to more diffraction
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Fourth (interference)
the combination of two or more waves that results
in a single wave
Its types:
A) constructive:
when crest(trough)+crest(trough)
and the amplitude will increase
B) destructive:
when trough(crest) + crest(trough)
and the amplitude will decrease

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Fifth (Standing wave)
a pattern of vibration that simulates a wave that is
standing still
Or
The result from the interference between the wave
you made and the reflected wave

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
Sixth (Resonance)
a phenomenon that occurs when two objects
naturally vibrate at the same frequency; the sound
produced by one object causes the other object to
vibrate
Resonant frequency
The frequency at which standing waves are made
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