Electricity CHAPTER 6

Structure of Atoms  Atoms are made of 3 particles  Protons-Positively charges  Found in Nucleus  Neutrons-No Charge  Found in Nucleus  Electrons-Negatively Charged  Found outside of Nucleus  Most of the time, Protons=Electrons  Electrically Neutral

Charged Atoms  When an atom gains or loses and electron, it becomes charged  Called an ion  Atoms cannot lose a proton and remain the same element  Protons are what determines what element an atom is.  1 proton=Hydrogen  3 protons=Lithium  Etc. See Periodic table  The number of protons is called the atomic number  Charges can be confusing…  When an atom GAINS an electron, it becomes negatively charged  Electrons are negatively charged  If it loses an electron, it becomes positively charged  More protons than electrons=more positive than negative  Charge is measured in Coulombs (C)

Static Electricity  Accumulation of excess charge on an object  Gained excess electrons  Shoes on carpet, hair on balloon, cloths in dryer  Because the object is negatively charged, it is attracted to objects with a positive charge  Opposite charges attract

Law of Conservation of Charge  Yep, another one…  Charge can be transferred, but it cannot be created or destroyed  Typically, it is electrons transferred, not protons

Charges Exert Forces  Unlike charges attract, like charges repel  The force depends on the distance and charge  Called Coulomb’s Law

Charges also create a field  Electric Field-area around charged particles that create a force  Indicated by arrows  Towards negative  Away from Positive

Strength of Electric Force  Electric force is stronger than gravitational force  Why don’t we feel it?  Most objects are electrically neutral

Conductors and Insulators  Conductor-allows electrons to easily pass  Best conductors are metal  Insulator-does not allow electrons to easily pass through  Plastics are great insulators

Charging  Charging by contact  Charged by touching or rubbing  Charging by Induction  Charged by nearby charged object  Does not need to touch object

Lightning  Storm clouds are arranged with negative charge on bottom  Becomes more negative than objects on Earth’s surface  Static discharges from cloud to surface 

Grounding  Connecting an object to Earth with a conductor  Reroutes lightning and electricity  Safety measure