Aim: How can we describe elementary charges? Electrostatics Aim: How can we describe elementary charges? Do Now: Define electrostatics from its name. What do you think it involves? Tape Demo: Rip two pieces of tape off each other and compare how they behave with each other and another students pieces. Make sure to know which pieces are top and bottom. Likes repel and opposites attract. What is observed? What can we say about the charges on the two pieces? Note: One piece has tape bent over so to tell which piece is which. Comparison done with a second set in front of class.

How can we define Electrostatics? Electro- Electricity/charged particles Static-stationary/ not moving Electrostatics- the study of stationary charges

Magic Tape What occurs when two tops or two bottoms come near each other? How about a top and bottom? Why does this happen? Tape Demo: Rip two pieces of tape off each other and compare how they behave with each other and another students pieces. Make sure to know which pieces are top and bottom. Likes repel and opposites attract. What is observed? What can we say about the charges on the two pieces? Note: One piece has tape bent over so to tell which piece is which. Comparison done with a second set in front of class.

ATOM REVIEW Matter is made up of small structures called ATOMS Within the NUCLEUS are two types of NUCLEONS At the center of each atom is a NUCLEUS Orbiting the NUCLEUS are ELECTRONS ELECTRONS NEGATIVE charge Orbit nucleus PROTONS NEUTRONS POSITIVE charge DO NOT MOVE under “normal conditions” Uncharged – NEUTRAL DO NOT MOVE under “normal conditions”

What are these charged particles? Name two charges: Protons and electrons Electron are ___________. Protons are ___________. Describe a neutral atom. A deficiency of electrons produces a ____ charge, while excess electrons produce a ______ charge. Student draws a neutral atom. Let students attempt on their own! ACTIVITY.

Charges Laws + + - - + - Like charges repel (move away) (+ +) (- -) Opposite charges attract (+ -) - - + -

Demonstration  Why does a charged object attract a neutral object?   - + +  + -     +  Ex. Rods and cloth

Pith Balls & Charges How will the pith ball react when brought in contact with a negatively charged rod? Place on front of desk and show what happens when a negatively charged rod is brought close. Allow students to explain why they think this is occurring. What happens when I place the ball in between my hand and rod? Pith balls acquires charge or rod and then gets repelled, which hits hand and grounds itself to have opposite charge and repels back to rod.

+ - Charged Objects Normally, objects are electrically NEUTRAL. They have even numbers of protons and electrons If an object LOSES electrons, it becomes POSITIVELY charged If an object GAINS electrons, it becomes NEGATIVELY charged + - Demonstrate with pith balls/packing peanuts/van de graff/sketchy tool LACK OF ELECTRONS EXCESS ELECTRONS

How do we describe static charge? Electrons build up in one object (due to friction – rubbing) and quickly jump to another object when touched causing an electric spark or shock.

Note: “q” is the variable letter The Coulomb The basic unit of charge is the Coulomb 1e=1.6x10-19C 1C=6.25x1018e (elementary charges) Proton: Charge= +1.6x10-19C=+1e Electron: Charge= -1.6x10-19C=+1e Note: “q” is the variable letter used for CHARGE What is the charge if I give it one electron? 2? 3? What if I take away one electron? What do you notice about the increments? Difference between conversions, 1C is a ton of elementary charges! 1e is a small coulomb charge!

Charged Objects Objects can only gain or lose multiples of ELEMENTARY CHARGE This plate is neutral , so the # of PROTONS = # of ELECTRONS Number of Electrons Lost Plate’s Elementary Charge Plate’s Coulomb Charge 1 +1e +1.6x10-19 C 2 +2e +3.2x10-19 C 3 +3e +4.8x10-19 C The plate LACKS ELECTRONS

Example #1 An object has a net charge of -8x10-18 C. How many excess electrons are on the object?

Envelope Activity Work with your table to make the following charge conversions.

Electron and Coulomb Conversions 1) Determine the net charge on Peter after he rubs his feetsie pajamas on a rug and gains an excess of 2.5x104 electrons. 2) A metal sphere has net negative charge of -4.0x10-8 Coulombs. Determine the number of excess electrons.

How is a lightning bolt produced? Clouds become NEGATIVE by rubbing against each other (friction) and picking up electrons. When this electron build up is large you see lightning

SUMMARY Describe the characteristics of a… Variable letter for charge? Proton Neutron Electron Variable letter for charge? Unit(s) for charge? 1 elementary charge = ? How do objects gain/lose charge? Describe the Law of Conservation of Charge