Static ElectricityCHAPTER 16: SECTIONS 1-4

Static Electricity Charge that remains in one area. Ben Franklin (1706-1790)

“Elektron” =amber in Greek carries a negative charge

Glass carries a positive charge

*negative and positive are arbitrary Rules of charge

Likes repel Unlikes attract No net charge can be created or destroyed

Charge on an Atomic Level Negative net charge is an excess of outer electrons Positive net charge is a deficiency of outer electrons Static charge is a result of a transfer of outer electrons

between materials.

Dry days are best for sustaining a static charge.

Water molecules are polar and can attract loose electrons.

On a wet day charge will “LEAK” away because of this attraction to the water molecules in the air.

On a dry day there is less moisture in the air and there are much fewer water molecules to “steal” electrons away.

BEST DAYS to build up a charge is a dry winter day. WHY?

Two Basic Types of Materials Conductors

Lots of loosely bound electrons that are free to move about within the material

Metals (silver, copper, and gold are the top 3)

Aqueous salts and acids/bases (ionic or polar covalent)

Humans (why?)

Insulators Tightly held electrons that are not free to move.

Wood, glass, plastic

Nonpolar covalent (sugar)

Semiconductors Few loose electrons

Silicon or Germanium doped with arsenic, boron, antimony

How to charge an object

Rubbing 2 objects together to transfer electrons from one to the other.

Bringing an neutral object

1. In contact with a charged object (CONDUCTION)

2. In close proximity to a charged object (INDUCTION)

*No charge is created or destroyed during these processes!

Conduction

Physical contact with a charge object allowing a transfer of electrons to or away from a neutral object.

Net charge acquired by the neutral object is the same as the charging object.

How is it done?

Induction

Close proximity to a charged object that causes separation of charges in the neutral object.

Net charge acquired by the neutral object is the opposite of the charging object.

Can create a net charge the same as the charging object if GROUNDING is used.

How it works?