ELECTRICITY

OUTSIDE NUCLEUS-ELECTRON CLOUD ATOMS Contain subatomic particles Subatomic particles: protons, neutrons, and electrons Protons and neutrons are made up of smaller subatomic particles called QUARKS PARTICLE SYMBOL MASS LOCATION PROTON p+ 1.67 X 10-24 g NUCLEUS NEUTRON n0 ELECTRON e- 1.1 X 10-29 g OUTSIDE NUCLEUS-ELECTRON CLOUD

The World is Filled With Electrical Charges Electric Field- force exerted by an e- on anything that has an electric charge Opposite charges attract; like charges repel

Static Electricity Electrical potential energy Net accumulation of electric charges on an object Static electrical discharge- movement of the electrons to relieve this build up Charging can occur through Friction Conduction Induction

Friction Rubbing two objects together Objects gain a negative charge by gaining electrons from another object

Conduction Direct contact of two objects Conductor- any material that allows electrons to move through it easily e- are loosely held in electric field Ex: metals

Semiconductors Solid material that has properties between conductors and insulators Important for electronics (computers, cell phones, MP3, etc.)

Insulators Material that doesn’t allow electrons to move through it easily e- are tightly held in electric field Ex: plastic, wood, rubber, glass

Induction Charging through an electric field without direct contact http://regentsprep.org/Regents/physics/phys03/aeleclab/induct.htm

Grounding using a conductor to transfer electric charges to the ground The ground is an infinite reservoir for electrons because of its large size

Electroscope Instrument that detects the presence of an electrical charge e- are transferred down the metal ball and down to the aluminum leaves the leaves become negatively charged and repel from each other

Electromagnets Temporary magnet formed when current passes through a wire coiled around an iron core Also called a solenoid Increase the strength by increasing the number of coils in the wire or by increasing the current

Generator Machine that produces an electric current by rotating a coil of wire in a magnetic field

Generator-How It Works Wire coil is wrapped around an iron core and placed between the poles of a permanent magnet Coil is rotated by an outside source of mechanical energy As the coil turns in the magnetic field an electric current flows through the wire When the coil turns so that the ends move past opposite ends of the magnet the current reverses directions The current changes direction twice with each revolution ALTERNATOR - generator used by a car

Electric Current The net movement of electric charges in one direction Symbol is I measured in amperes (amps) Direct current batteries Alternating current Wall outlet, electric generator

Voltage (Potential Difference) Force that causes electric charges to flow Flows from high voltage to low voltage Measured in volts Symbol is V

Resistance Tendency of a material to resist the flow of electrons Conductors have much less resistance and insulators have high resistance Symbol is R Measured in ohms (Ω) Resistance in a wire increases As the temperature increases As the wire gets longer As the wire gets thinner (diameter decreases)

Ohm’s Law The relationship between current, voltage, and resistance in a circuit I = __V__ R