Download ELECTRICITY

ELECTRICITY
ELECTRIC CHARGE
• SI unit for electric charge is Coulomb (C).
ELECTRIC FORCE
• Force of attraction
or repulsion
• LIKE charges
REPEL
• OPPOSITE charges
ATTRACT
STATIC ELECTRICITY
• Static Discharge –
when a pathway for
charges to move
forms suddenly
– Ex: Lightening, shock
CHARGING
1. Charging by Friction – friction between two
objects transfers electrons.
•
EX: Balloon and hair; electrons move from the hair to the
balloon and now the balloon is neg. and the hair is pos.
2. Charging by Contact – when someone
touches a something to allow the charge to
travel.
•
EX: When a person touches a generator to cause their
hair to stand up
3. Charging by Induction – when charge is
transferred without contact
•
EX: when you touch a doorknob and get shocked – neg.
charges in your hand cause charges to move in the metal.
ELECTRIC CURRENT
• Continuous flow of electric charge
• The SI unit for electric current is ampere
(A), or amp
TYPES OF CURRENTS
• Direct Current (DC) – charge flows in
ONLY ONE direction
– EX: Flashlight
• Alternating Current – (AC) – charge that
can reverse its direction in several ways.
– EX: House
CONDUCTORS AND
INSULATORS
• Conductors – material
where charge can
flow easily.
– Metals
• Insulators – material
through which charge
cannot flow easily.
– Coating on wires,
wood, plastic, rubber,
glass, and air
RESISTANCE
• Opposes the flow of electric charges
• SI unit for resistance is Ohm
• A materials thickness, length, and
temperature affect its resistance. As temp.
increases the resistance increases
OHM’S LAW
V = I x R or I = V
R
V = voltage
I = Current
R = resistance
* Increasing the voltage increases the Current
Electricity Quiz
1.
2.
•
•
•
•
•
•
•
•
What is the SI unit for electric charge?
Like charges ______ while opposite charges
________.
What is it called when a pathway for charges to move
forms suddenly?
Charging by __________– when charge is transferred
without contact
What is SI unit for electric current?
What current flows only one direction?
What is a material that a charge can flow easily?
What is a material that a charge cannot flow easily?
What is SI unit for resistance?
A material’s ________, _________, and _________
affect its resistance.
Answers
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Coulomb (C).
Repel, attract
Static discharge
Induction
ampere (A), or amp
Direct current
Conductors
Insulators
Ohm
thickness, length, and temperature
ELECTRIC CIRCUITS
ELECTRIC CIRCUITS
• Complete path through which charge can
flow.
• Switches can be opened to allow
electricity to flow or closed.
TYPES OF CIRCUITS
• Series Circuit –
charge has ONLY
ONE way to flow
(direct current)
– If one element stops
working they all stop
– EX: Flashlight, car
• Parallel Circuit –
charge can flow
through TWO or
MORE pathways
(alternating current).
– If one element stops
functioning the rest will
still operate
– EX: House
POWER AND ENERGY
• Electrical power – the arte at which
electrical energy is converted to another
form of energy.
• SI unit for electrical power is Watt (w)
• P=IxV
ELECTRICAL SAFETY
•
•
•
Fuse – prevents
current overload in a
circuit
Circuit Breaker –
switch that opens
when the current in
a circuit is too high
Grounding – transfer
of excess charge
through a conductor
to Earth
Electric Circuits Quiz
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
What is a series circuit?
What is an example of a series circuit?
What is a parallel circuit?
What is an example of a parallel circuit?
What is the Scientific Unit for electrical power?
What is the definition of electrical power?
What is a circuit breaker?
What does a fuse prevent?
What is grounding?
What is the Scientific Unit for electric current?
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Series Circuit – charge has ONLY ONE way to flow (direct
current) If one element stops working they all stop
EX: Flashlight, car
Parallel Circuit – charge can flow through TWO or MORE
pathways (alternating current). If one element stops functioning
the rest will still operate
House
Watt
the arte at which electrical energy is converted to another form of
energy.
switch that opens when the current in a circuit is too high
current overload in a circuit
transfer of excess charge through a conductor to Earth
Ampere or Amp
Magnetism
• Magnetic Force- LIKE repels LIKE, LIKE
attracts UNLIKE
• Magnetic Field- Surround a magnetic and
always starts at the North
Pole and extends
toward
the South Pole
• Ferromagnetic Materials- materials that
are easily magnetized and demagnetized.
a. Magnetized objects have ALIGNED
magnetic domains.
b. Demagnetized materials have
RANDOM magnetic domains.
• Permanent Magnets- always have aligned
domains and it is very difficult for them to
lose their magnetism.
ELECTROMAGNETISM
• Electromagnetic Force- caused by electric
forces
a. Moving electric charges create a
magnetic field
b. Changing the current in an
electromagnet controls the strength and
direction of its magnetic field
• Electromagnetic devices- convert electrical
energy into motion that can do work
1. Galvanometers- uses a coil of
current carrying wire that produces a
magnetic field to measure small amounts
of current that moves a pointer.
Ex. Gas gauge
2. Electric Motors- uses an electromagnet
to turn an axle
3. Loudspeaker- a magnetic force moves the
coil back and forth causing the thin
membrane to vibrate producing sound
waves