January 13, 2010 charge

Last time we created top and bottom “types” of tapes. Two TOP tapes will: A. Attract B. Repel C. Might do either.

two bottom tapes will attract repel ignore each other

a top tape and a bottom tape will attract repel not interact

when two “charged” tapes move together- the interaction increases the interaction decreases the interaction does not depend on the distance.

how many types of charge have you observed? one two three four

Could there be a third kind of charge? Yes No Not Sure Let’s think about this.

Weird Science Type 1 (+) Type II (-) Type III () R A Type 1 (+)

From whence this charge??? Easily Removed - +

The electric charge on an electron is very small and it is NEGATIVE: -1.6 x 10-19 Coulombs. The protons found at the center of atoms have the same amount of charge as the electron except it is a POSITIVE electric charge: +1.6 x 10-19 Coulomb

Materials Two kinds of materials: Insulators Conductors Electrons and Protons are tightly bound to their positions. Hard to move them around. Conductors Electrons are easily removed and moved around. Electrons are said to be MOBILE charges. There are other kinds of materials that we will not discuss: semiconductors, semi-metals

Review: Ways to charge an object Rubbing or bond breaking (same thing) Transfer Direct transfer Polarization Induction ??????

Same as before: Polarization

The Triboelectric Series When two of the following materials are rubbed together under ordinary circumstances, the top listed material becomes positively charged and the lower listed material becomes negatively charged. MORE POSITIVE rabbit's fur glass mica nylon wool cat's fur silk paper cotton wood acrylic cellophane tape polystyrene polyethylene rubber balloon saran wrap MORE NEGATIVE No! No! No! No!

Induction

Polarize

Ground

Remove Ground

Positive !