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 n o = 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 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: Step 1:Step 2: brushes ____________in contact with commutator brushes ____________in contact with commutator Inertia keeps coil spinning Inertia keeps coil spinning

Spinning Motor Step 3:Step 4: commutator _____________ commutator current – keeps spinning reverses current commutator _____________ commutator current – keeps spinning reverses current again - keeps again - keeps spinning 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