Transcript BW March 11 - Elyria Catholic High School

BW
• Explain what problems electrical power
outages can cause in your home and in your
communities. You must think of at least 5.
Chapter 11
Electricity
I. Electricity: Energy Carrier
A. Electrons carry negative charges
1. Like charges repel
2. Unlike chares attract (opposites attract)
3. Conservation of chargeElectrons are Not created or
Destroyed. They do TRANSFER
4. The transfer of electrons from one atom to
the next creates a flow of electrons called
electric current.
Bellwork
• Explain the conservation of charge and give an
example of a situation where it is conserved.
5. Electrical Force
a. is measure in Coulombs =C= 6.25 billion billion
electrons
b. electrical force (F) = k(q1q2)
d²
k = 9 x10⁹
…it’s just a number!
q= charge of a particle
d= distance between the two particles
C is like N (force of gravity) …but can attract and
repel
6. Charge Polarization
• When electrons move they create postive and
negative charges
Demonstrations
1.
2.
3.
4.
5.
6.
7.
Fur and metal plate
Shock mrs. Bailey
Make the pom pom hair stand up
Make the string stand up
Repelusion
Student hair
Electric Storage
BW-Read Driving Darkness away
1. List 5 types of filaments used to make a light
bulb.
2. What was the filament that finally worked
and how long did it burn?
3. After the light bulb was invented, how did
the city of new york react?
B. Electric Current
1. Conduction Electrons FLOW in metals making
an electric current.
2. The rate of current is measured in AMPERES
AMP= 1 coulomb of charge per second
3. Volts (V) indicate strength or pressure of an
electrical current.
- When electrons flow they have to flow from
high potential (stored) energy to low potential
energy
4. Amps indicate how many electrons flow past
a specific point in a circuit in a given length of
time
Re-Volt- ing
• Lightning strikes discharge 100 million volts of
electricity
• Taking off sweater can generate 30,000 volts
• Using a comb =10,000 volts
• Carpet walking with socks- 1000 volts
• 600 volts in an electric eel’s tail
3. Watts total electrical energy being used
Volts x Amps = Watts
kilowatt=1000 Watts
Each house uses approximately 200-300
kilowatts a month
That’s a Lotta Light
Electricity around the world
*North America 3.5 billion kilowatts
*Central and S.America .5 billion kilowatts
*Western Europe .3 billion kilowatts
*Eastern Europe and Russia 1.5 billion
* Africa .2 billion kilowatts
BW
1. How many watts are there in a light that uses
12 volts and 10 amps? (Remember to label!)
2. Compare the terms volts and amperes to
water in a hose.
Resistance
• How hard is it to push electrons through
different materials. (ohms) Ω
• Amps= volts / ohms
Symbol for resistance on circuit:
In a series you add up all the resistance!
Overload= too much current (Amps)
• to protect from overload, electricians add
fuses in series with the circuit
– Fuse – thin metal that melts at certain amps and
breaks the circuit
– “We’ve blown the fuse” or “circuit breaker”
D. History
1. Thales of Miletus Greek Scientist experiments
with amber (hardened tree sap ) and rubbed
it with fur attracts feathers.
2. Electricity comes from the Greek work
elecktron which means Amber
3. Electricity was coined by Queen Elizabeth’s
Doctor in the 1600s
4. 1780 Luigi Galvani, discovered the sparks of a
machine makes the legs of a dead frog twitch
5. 1800 Volta discovers continuous electricity.
6. Thomas Edison in 1876 created the light bulb
They tried cotton, flax, jute silks, cords, manila
hemp, chinese and raw silk, horsehair, fish
linen, teak, spruce, boxwood, vulcanized
rubber, cork, celluloid, grass, linen twine, tar
paper, wrapping paper, cardboard, tissue paper