 Brought to you by Barr/Batten

 Does your clock radio wake you in the morning?  The source of electrical energy lies in the forces between electric charges in atoms

 Electric Charges o Positive (Proton) o Negative (Electron) o Neutral (Neutron) o Atoms are neutral so # of protons and electrons are equal

 Forces between charges o Like charges repel o Opposite charges attract o Charge decreases with distance o Objects do not have to be touching for electric charges to exert force

 Making objects electrically charged o Charging by contact Atoms need to touch– rubbing balloon on your hair, clothes in the dryer o Charging by induction No electric charge transfer, just movement of the charges– after you rub the balloon you can stick it to the wall  Conductors and Insulators o Conductors– hold electrons loosely allow them to flow easily o Insulators- hold electrons tightly do not allow them to flow easily

 Static Charge Imbalance of electric charge on an object o Electric Discharge Movement of static charge from on object to another– spark when you touch the doorknob o Lightning Example of static discharge o Lightning Safety On average lightning strikes about 400 people in the US If the time between lightning and thunder is less than 30 sec, seek shelter for 30 min until after the last flash o Grounding The process of providing a path to drain excess charge into Earth – lightning rods

 What is it? o Flow of electric charge  Unit for Current? o SI unit is the ampere, the symbol is A o 1 ampere means an enormous number of electrons– like a billion billon– flowing into and out of the wire every second

 Simple Electric circuit o The closed path which electric charges can flow through  Voltage o Measure of the amount of electrical energy transferred by an electric charge o Ohm’s Law– the relationship between voltage, current and resistance in a circuit Voltage(in volts)= current (in amperes) x resistance (in ohms) V=IR  Series circuit o Devices connected so there is only on path  Parallel circuit o Devices connected so there is more than one path for the current to follow

 Magnets o Magnetic Poles Two ends of a magnet– one is North and one is South o Forces between poles Magnetic poles exert force on other magnets—like attract, opposites repel o Magnetic Fields Magnetic force that surrounds the magnet  Magnetic Materials o Only metals that contain, iron, cobalt, & nickel

 Electromagnetism o Electricity and magnetism are different, but related o A current carrying wire wrapped around an iron core o Strength is dependent on the current flowing in the wire  Generating Electric Current o if a magnet is moved through a wire loop o Or is a wire loop is moved in a magnet o Current can be generated