Transcript ELECTROMAGNETISM - Ste. Genevieve R

ELECTROMAGNETISM
Bell Work
Welcome back, I hope you had a great break!
(Write each statement then decide if it is
true or false, if false correct)
1. The basic particles of an atom are
protons, neutrons, and nuclei.
2. Particles that make up an atom have no
charge.
3. Electrons are negatively charged.
Electricity 1.1 Vocab
• Electric charge – a property that allows
an object to exert an electric force on
another object without touching it.
Unlike charges
attract.
Like charges repel.
1.1 Vocab Cont.
• Electric field – the space around a
particle through which an electric charge
can exert force
1.1 Vocab Cont.
• Static charge – a buildup of electric
charge in an object caused by the
presence of many particles with the same
charge
At first, a balloon and a glass rod
each have balanced, neutral charges.
At first, a balloon and a glass rod
each have balanced, neutral charges.
When they touch,
electrons move from
the rod to the balloon.
Afterwards, the balloon has
a negative charge, and the
rod has a positive charge.
1.1 Vocab Cont.
• Induction – the buildup of a
charge without direct contact
Bell Work
Draw a picture and explain each
answer.
1. How do two positive particles interact?
2. How do two negative particles interact?
3. How do a positive and a negative
particle interact?
Bell Work
Please answer the following questions using
complete sentences.
1. A sock and a shirt from the dryer stick
together. What does this tell you about the
charges on the sock and shirt?
2. You walk over a rug and get a shock from a
doorknob. What do the materials of the rug
and the shoes have to do with the type of
charge your body had?
Assignment
Read pg 18- 25 then…
Choose one of the following to complete
• Make a PowerPoint for the vocab words on
page 18. Each word should have 2 slides. First
slide: word, definition, and a sentence in your
own words. Second slide: word and a picture.
Word
Definition
• Make a 4 square chart 
For each of the vocab
Use in a
Draw a
sentence in picture.
words on page 18.
your own
words
1.2 Vocab
Electric potential – the amount of
electric potential energy per unit
charge at a certain position in an
electric field.
Volt – equal to one joule of energy per
coulomb of charge
Conductor – a material that allows
an electric charge to pass through
it easily
Insulator – a material that does not
easily allow a charge to pass
through it.
Resistance – the property of a
material that determines how
easily a charge can move through
it
Ohms – the unit for measuring
electrical resistance
Grounding – providing a harmless,
low-resistance path (a ground) for
electricity to follow
Bell Work 5/12/11
Draw a picture and explain what
happens when there is
lightning. (hint look at pg 25)
Bell Work 5/11/11
Please read page 17 about
Electric Eels. Write 3
sentences about what you
learned and answer #1.
Please use complete
sentences.
Bell Work 5/12/11
Make a chart with at least 5
conductors and 5 insulators
in it.
Bell Work 5/13/11
1. What is electric potential?
2. What 3 factors affect how much electrical
resistance an object has?
3. How can a lightning rod protect a
building from fire?
Bell Work 5/16/11
1. Why do lightning rods work better if they
are placed high up, closer to the lightning
charge?
2. Could the same material be used as both
a conductor and an insulator? Explain
your answer.
Bell Work 5/17/11
1. Draw a picture of a wire with low resistance.
2. Draw a picture of a wire with high resistance.
3. What might wire made with low resistance be
used in?
4. What might wire with high electrical resistance
be used in?
Bell Work
1. How much resistance does
a superconducting material
have? (pg 24)
2. What is a ground cable?
(pg 25)
1.3 Notes
Electric Current – the flow of
charge (+,-) through a material.
Electric currents produce
magnetic fields --spinning/moving electrons.
Circuit – complete path through which
electric charges can flow.
1. circuit has a source of electrical
energy.
2. circuits have devices that are run
by
electrical energy.
3. electric circuits are connected by
conducing
wires and a switch.
Ampere – the standard unit of measure for
current
Ohm’s law – shows relationship between
current, voltage, and resistance
Current = Voltage
Resistance
I=V
R
Electric cell – produces electric current
using the chemical or physical
properties of different materials
Primary cell – produce electric current
through chemical reactions until the
chemicals are all used up
Storage cell – produce electric current
through chemical reactions that can be
reversed in the battery
Bell Work 5/19/11
Make a Venn diagram
comparing and contrasting
electric current and static
discharge.
Bell Work 5/24/10
Good morning. Please get
out your study guide and
begin reviewing for the final.
Bell Work
1. Where do solar cells get their
energy?
2. What kind of battery can be charged
by reversing chemical reactions?
3. What does an ohmmeter measure?
4. In which direction do electrons flow
when a storage cell is being
charged?
Bell Work 5/25/11
1. An electrical pathway has a voltage of
240 volts and a current of 10 amperes.
What is the resistance?
2. A 240-volt air conditioner has a
resistance of 8 ohms. What is the
current?
3. An electrical pathway has a current of
1.2 amperes and resistance of 40
ohms. What is the voltage?
Bell Work
Write a paragraph about your
favorite part of science class
this year and your least
favorite part of science class
this year
- Then get out your study guide
and review
Magnetism – The attraction of a magnet for
another object.
Magnetic pole – end of a magnet, a pole is the
area of a magnet where the magnetic effect is
strongest. Pg 18
alike poles repel and opposites
poles attract each other.
Magnetic Fields - the region of magnetic force
around a magnet.
Inside a Magnet
Atom – smallest particle of an element that has
the properties of that element.
Element – Is on of about 100 basic materials that
make up all matter.
Nucleus – Center of an atom that contains the
PROTON and the NEUTRON.
Proton – the positive charged particle of an atom.
Neutron – Contain mass only (NO CHARGE).
Electron – Very small particle Found circling the
nucleus with a negative charge.
•The spinning of the electrons in an atom causes
an magnetic field.
Magnetic domain – when a large portion of the
atoms in a material are lined up in the same way.
•In a magnetized material all or most of the
domains are arranged in the same direction.
•Iron is a substance that will undergo magnetism
because the domains can be aligned to have a
strong magnet.
Temporary magnets – when domains are
alligned for a short period of time. Like placing a
magnet on a group of paper clips
Permanent magnet – A magnet made of a
material that keeps its magnetism. The more
iron in the magnet the better (stronger) the
magnet.
Earth as a Magnet
Although not completely understood the popular
theory is --- the molten iron and nickel core is
spinning causing the generation of a magnetic
field around Earth.
Earth has both a North and South magnet pole,
just as a bar magnet does.
Magnetic Declination – the angle between
geographic north (true north) and the north to
which a compass needle points.
• Magnetic north is 1250 km (776 miles) from
geographic north.
• Magnetosphere -
The Earth will actually make iron object
magnetized over a long period of time, if the
object doesn’t move.
The rock that forms from lava will have a
magnetic domain facing the poles of the Earth.
Over 800,000 year the magnet poles of the
Earth will swap. Don't know why, but da do!!!
Electric Current – the flow of charge (+,-)
through a material.
Electric currents produce magnetic fields --spinning/moving electrons.
Circuit – complete path through which electric
charges can flow.
1. circuit has a source of electrical energy.
2. circuits have devices that are run by
electrical energy.
3. electric circuits are connected by conducing
wires and a switch.
Flow of electrons,
energy source
Resistance – the opposition to the movement of
charges flowing through a material.
Superconductors – materials that have no
resistance to electrical flow. NO LOSS OF
ENERGY occurs in a superconductor.
Solenoid – a current carrying coil of wire with
many loops.
Electromagnet – a solenoid with a ferromagnetic
core. Can be turned off and on.
B
• Resistor: A resistor uses electrical energy
or “resists” the flow of charge in an
electrical circuit.
Light bulb, any electrical appliance.
Electricity
• The unit of current is the ampere or “amp”.
• It tells the amount of charge flowing past a
point at any given second.
• ALL MAGNETISM IS CAUSED BY
MOVEMENT OF CHARGES.
http://www.pbs.org/wgbh/amex/edison/sfeature/ac
dc.html
• Conductors: Electrons are loosely bound to
the atom and electrical currents move freely
through the wire.
• Copper, aluminum, silver and iron.
• Insulators: Electrons are bound tightly to
atom and do not flow easily.
• Rubber, glass, plastic, sand, wood.
• Static Electricity: Charges build up, but do
not flow.
Caused by:
• Friction-transfer of electrons from one
object to another by rubbing.
• Ex: clothes in a dryer
• Conduction: the transfer of electrons by
direct contact.
• Ex: touching a car door or someone and
getting shocked!
• Induction: the movement of electrons to one
part of an object caused by the electric field
of another object.
• Voltage: The force that pushes the electrical
charge through the wire.
• Series Circuit: Only one path for the
current to take.
• Pro: Simple and cheap to make
• Cons: 1. If one light goes out, they all do
• Lights become dimmer as you add more
bulbs (less current and more resistance!)
• Parallel Circuit: Several paths for the current
• Pro: Individual bulbs can be turned on and of
without affecting each other. Ex:
• Household circuits
A scientist is experimenting with bacteria that are
one micron in diameter and that reproduce by
dividing every minute into two bacteria. At
12:00 PM, she puts a single organism in a
container. At precisely 1:00 PM, the container
is full.
1. At what time was the container half full?
2.There are twelve identical-looking balls, but one is
either heavier or lighter than the other eleven. How
can you determine which is the odd ball and find out
whether this ball is heavier or lighter than the others
using only three weighings with a balance?
Bell Work
1. What is going to be the most
difficult part about building
your box?
2. What is going to be the
easiest part about building
your box?
Bell Work
If you could make 3 changes
to your box what would they
be? Please write a
paragraph to answer the
question.