Transcript charging by - Mrs. Wiedeman

Electricity and Magnetism
Chapter 7 Section 1
Chapter 8 Sections 2 & 3
Chapter 7 Section 1
Electric Charge
Positive and Negative Charge
Atoms have particles ___________________,
neutrons, and ___________________
p+ = _____ charge no = no charge e- = ______
charge
Same # of p+ and _______ = atoms are
electrically neutral
Transferring Charge
Some electrons are bound _____________ to
some objects
e- bound to ______________ more than carpet
Shoe _______________ e- = - charged
Carpet _____________ e- = + charged
Static Electricity: accumulation of _________
electric charge
Conservation of Charge
Def: charge can be
_________________
from object to object,
but it cannot be
_______________ or
destroyed.
Charges Exert Forces
Clingy clothes from a
dryer
Opposites _________
Force depends on
_________________
and size of charge
Positive clothes like
________________
clothes
Like charges repel
Opposite charges attract
Like charges repel
Electric vs. Gravitational Force
________________ force from p+ and e- in H
atom is 1039 times stronger than
_________________________ force
Most things gravity force is stronger than
electrical
Conductors and Insulators
Conductor: material where e- move
____________________
Metals best conductors – _____________
____________________ material where
e- do NOT move easily
Plastics, wood, rubber, ______________
Charging Objects
Rubbing materials can ______________
e- - one is (+) the other is (-)  charging
by ______________
Charge by Induction
Def: rearrangement of __________________ on
neutral object by nearby charged object.
Lightning
Static ________________: transfer of
charge because of a ________________
of static electricity
Clouds have __________________ of air
and rain  areas of + and – charge build
Lightning is _________________ between
cloud and ground
Thunder
Lightning ___________ e- from
atmosphere and produces heat increase
__________________
Atoms expand ________________ and
release sound waves
Earth is struck ____________ times every
second
Grounding
_________________ effects from charge
build up
If there is a ______________ to earth –
relieves build up
Grounded – it will transfer any
________________ charge to earth (big
neutral object)
Electroscope
Chapter 8 Section 2
Electricity and Magnetism
Basics of Magnets
Magnetic ______________: exerts a
force other magnetic objects
Magnetic ______________: where
magnetic force is strongest
Field goes from North to _____________
Earth’s Magnetic Field
Compass
Compass needle is small _______________ –
lines up with earth’s magnetic field
From ___________________ magnetic pole to
_________________ magnetic pole
Electric Current and Magnetism
_______________ electric currents create
magnetic field in direction of current
_________________ increases = increase
____________________ field
Electromagnets
Def: ____________________ magnet
made by wrapping a ______________ coil
carrying a current around an ___________
core
Magnetic field in ______________ is
stronger than ________________ wire
_____________________: single wire
wrapped in cylindrical coil
Electromagnets
_______________
_______________
Properties of Electromagnets
Temporary b/c when _______________
stops – _________________ stops
Increase strength – more ____________
in solenoid or more ______________
Useful b/c magnetic strength can be
__________________ – used for work –
motors and speakers
Making Sound
CD changing
______________ info
 changing
____________
current
Electromagnet is
______________ or
repelled by
permanent magnet
Moves speaker
_____________ to
make music
Rotating Electromagnets
______________ current to change poles
 electromagnet ________________
Galvanometers
Def: use electromagnet to measure
____________________ current
Used in ______________ in cars
Electric Motors
Def: device that changes _________________
energy to ____________________ energy
Simple Electric Motor
3 main parts: wire ____________, permanent
___________________ and battery
Also have brushes – conducting
_____________ connected to battery and a
commutator – ___________ conducting metal
ring
Spinning Motor
Commutator _______________ with coil as current runs
through
Step 1:
Step 2:
brushes ____________in
contact with commutator
Inertia keeps coil spinning
Spinning Motor
Step 3:
commutator _____________
current – keeps spinning
Step 4:
commutator
reverses current
again - keeps
spinning
Chapter 8 Section 3
Producing Electric Current
Mechanical to Electrical Energy
Moving ________________ through
magnetic field  ______________ current
Moving _______________ through wire
loop  electric current
Electromagnetic induction: creating a
current by _________________ magnetic
field
Generators
Def: uses electromagnetic ________________
to transform mechanical energy to
____________________.
Move a _____________ in a permanent magnet
Switching Current Directions
Each half-turn poles of coil _________________
 current switches direction
Coil keeps rotating current periodically changes
____________________
US generators rotate ____________ times/sec =
3,600 rotations/min
Using Generators
This type of generator is used in cars =
________________________
Lights, accessories, spark plugs
Running _________________ turns coil
Electricity to Your Home
Huge generators in power plants rotate the
permanent ____________________ and the coil
stays still
Electricity is generated in the ______________
A _______________________: (large wheel
rotates when pushed by water, wind or steam)
spins the ____________________
Some use thermal energy – heat water – turn
turbine (_____________________ energy) –
spin generator (electrical energy)
Pg. 241
Direct and Alternating Currents
Current in ________________ vs. electric
generator
Battery – ______________ Current (DC):
flows in one direction through wire
Wall Outlet – Alternating Current (AC):
_____________________ direction of
current in a regular pattern
60 cycles/s = 60 ________  changes
direction ___________ times each second
Transmitting Electrical Energy
Electricity to your house
Goes through ______________ lines –
energy  heat due to
____________________ in wires
Reduce heat/resistance  send at high
voltage __________________ V
BUT can’t use that high of voltage  goes
through __________________
Transformers
Def: ___________________ or decreases the
voltage of an alternating current.
Has ________________ coil and secondary coil
wrapped around same iron core
Current goes in primary coil  magnetizes core
As AC current changes direction the
_________________ of magnet change
Changing poles  creates electric current in
_____________________ coil
Types of Transformers
__________________: increases voltage –
outgoing is higher
Primary coil smaller than secondary
__________________: decreases voltage –
outgoing is lower
Primary coil is larger than secondary
Transmitting AC
Generator  step-__________ tran. 
high voltage lines  step-___________
tran.  house