all matter is made up of atoms atoms are made up of protons, electrons and neutrons protons and...
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All matter is made up of atoms atoms are made up of protons,
electrons and neutrons Protons and electrons can transmit
energy in the form of electricity When 2 different materials are brought
into close contract some electrons move to the other material
Causes the material to become electrically charged (positive charge or negative charge)
Negatively charged-more electrons, less protons
Positively charged-more protons, less electrons
Static electricity is produced from the buildup of positive and negative charges
Principles of Electricity: Opposite charges attract Like charges repel
When a charged balloon is brought near a wall, its extra negative charges repel the negative charges on the wall
The negative charges move to the other side of the wall
The wall becomes positively charged The balloon has a negative charge
causing it to be attracted to the wall and stick
Conductors: Electrons move through a material
easily Can cause a spark Ex: human tissue touching metal
doorknob
Insulators: Electrons do not flow easily through a
material Ex: human tissue touching plaster will
not cause an electric spark
It is dangerous to touch a bare wires Grounding wires of an appliance
connects the metal case to the ground through the household wiring
If a dangerous charge builds up the grounding wire enables the appliance to share the change with the ground
Grounding wires protect us from getting dangerous shocks
Produced by static electricity Negative charges build up in a cloud The ground has a positive charge When enough negative charges build
up they form a path to the ground Surge of electric energy heats the air to
glow-we see lightning Heat makes the air expand rapidly-we
hear thunder Lightning has high electric energy,
which is deadly
A path along which charged particles can travel
Electrons move through the wires and bulbs Consist of a source of electricity, devices
and connecting wires The source of electricity starts pulling and
pushing on the electrons and the electrons start flowing to the positive end of the source
A flow of charged particles moving through a circuit is called a current
Electrons move from negative to positive
Sources of electricity are rated by voltage As the voltage becomes greater, more
negative and positive charges can build up at one end
Resistor-opposes a flow of electrons It makes the current smaller by opposing
the flow of electrons The lamp could blow out without the resistor The resistor reduces the current of electrons
flowing through the lamp to a safe level
Short circuit could occur if the current is not reduced
If the current is not reduced, electrons will collide causing the wires to heat up
This heat could cause a fire
Only one path for the electric current Their voltages are added together Increased crowding of electrons at the
negative end of one battery Increased removal of electrons at the
positive end of the other battery Puts more force on electrons in the wires
and bulbs, which produces more current Light bulbs act as a resistor to prevent a
short circuit from occurring The flow of charges is the same at any
point
More than one path for current Electricity source makes each path feel
the same overcrowding of electrons Total current increases when another
path is added, even though another resistor is present
Current in each path depends on the strength of its resistor
Currents are added together to find the total current
Total current is the same at any point
Incomplete circuit Switch is in the off position There is no current Electrical devices do not receive
electric energy Copy circuit 1 in Notebook
Complete path for a current Current flows in the wires and devices Current transfers energy to the device Switch is in the on position or closed Copy Circuit 2 in Notebook
Attract metal objects made of iron, cobalt or nickel
Attract and repel other magnets Have 2 poles: north-seeking pole and a
south-seeking pole South pole of one magnet repels the
south pole of another A north magnetic pole attracts a south
magnetic pole The attraction is strongest at the poles
Magnetism comes from the motions of electrons in atoms
Moving electrons cause atoms to line up in the same direction
Permanent magnets-atoms always stay lined up
If brought near and object that is nonmetallic, there is no attraction
Devices that are made magnetic by an electric current
Magnetism results from moving electrons in a current-carrying wire
If brought near a nonmetallic object, there is no attraction
Is the area around a magnet in which other magnets can feel attraction or repulsion
Magnetic force moves from the north pole to the south pole and form closed loops
Attraction or repulsion is strongest where the arrows are most crowded
Tilt of Earth’s axis causes the magnetic poles to be off true geographic north and south poles
Magnetic field is not evenly shaped Compass needle always points to the
magnetic north pole Earth’s magnetism is likely caused by
electrical currents in a fluid metal layer around Earth’s inner core
Used to power toys, elevators, fans, air compressors, cranes, some cars and bicycles
The spinning force comes from an electromagnet
A loop of wire is placed between 2 permanent magnets
When current passes through the wire, the loop becomes an electromagnet
Magnetic resonance imaging (MRI) Strong magnetic field produced by
electromagnets cause the nuclei in the patients body to behave like magnets and line up with the magnetic field
This enables radio waves to produce images of tissues inside the body
Speakers depend on electromagnets to operate
Cone in a speaker has an electromagnet
Current passes through the electromagnet causing the cone to vibrate and produce sound
A device that produces a current in a solution
Use chemical reactions to produce an electric current
Charged particles always move in the same direction-direct current
Consists of 2 different metal plates in a solution
Produces a voltage-the difference in the amount of potential energy between the plate
Voltage is measured in volts
The amount if current can be measured by an ammeter and the unit is ampere or amp
Produce an electric current using a moist conducting paste
Chemical reactions between the paste and the plates produce a current
Ex: battery
Uses mechanical energy to make electricity
It produces an alternating current Electric power plants use generators to
produce electricity for homes and businesses
Transformers are used to increase or decrease the voltage of the current
Electric current produced by huge generators
Power lines connect the power plants to homes in cities and towns
Electric current from a generator first passes through a transformer that increases the voltage anywhere from 120,000 to 500,00 volts
Before the current comes into our homes it passes through another transformer that decreases the voltage
Household circuits use 120 volts The total current for an entire house is
100 or 200 amps You can run two appliances on the
same circuit, which has 20 amps, as long as they do not use more amps combined
Short circuits occur when too much current flows through a wire
Fuses and circuit breakers protect homes from catching on fire
Any form of energy can be changed into other forms
Electrical energy can be changed into 4 other types of energy
1.Mechanical Energy Electric energy changes into
mechanical when any device that uses a motor is used
Examples: food blenders, electric fans, power tools
2. Heat Coils get very hot because of an
electric current Electrons from the current collide with
the atoms in the coils Temperature of the coils rise Ex: heaters, electric blankets, toasters,
hair dryer3. Sound Current causes electromagnets to
move a diaphragm back & forth producing sound waves
Ex: speakers
4. Light 2 types of light bulbs1. Incandescent Contain a thin metal wire or filament
that acts like a resistor Electric current heats it causing the
filament to give off heat and visible light
Only 12% of the energy is light Rest of energy is wasted as heat
2. Fluorescent Produce more light than heat Series of collisions causes gas inside
the glass to produce light Fluorescent coating on the outside
glows
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