Electrostatics The study of electric charges

The Three Subatomic Particles – A Review Proton – Positive Charge (+), p + Neutron – No Charge (0), n 0 Electron – Negative Change (-), e - In physics, “charge” is represented by the letter “q”

Electric Charges on Objects A charged object has an unequal balance of positive and negative charges Objects can be charged two ways… Positive (+), such as vinyl and rubber Negative (-), such as fur, glass, and wool

How to Make a Charged Object (or, How to Transfer Charge) Friction or Contact Rubbing two objects together, or even just touching them, causes elctrons to move from the atoms of one object to the atoms of another object Scuffing socks on the floor, rubbing a balloon on your hear, Swiffer dusters Induction Electrons “jump” from one object to another when they are brought in close contact, but do not touch Using a charged balloon to raise the hairs on your arm, Van de Graaff generator

Properties of Charged Objects Like charges repel, unlike (opposite) charges attract Charges are not created, or destroyed – they are separated or combined (moved) Electrons added to, or removed from, atoms Charges exert a force on other charges over a distance

Because there’s a force, there are vectors Electric force vectors show the Electric Field ALWAYS point from (+) to (-) charges For a single charge… + - POSITIVE CHARGENEGATIVE CHARGE

For Two Charges… Equal but opposite charges Two like charges (positive or negative)

Magnets -Magnets have North and South poles -If you break a magnet the broken pieces will still have North and South Poles - Magnets produce magnetic fields that look similar to electrical fields

Conductors & Insulators Conductors allow charge to move easily through them Metals Insulators DO NOT allow charge to move easily through them Wood, Styrofoam Materials usually exhibit the same property for heat transfer

The Unit of Charge Called a Coulomb (C) 1 Coulomb (C) has a charge equal to 6.25 x electrons Charge of 1 electron = -1.6 x C

Units of Charge The coulomb is actually a very large unit for static electricity. We need to use the metric prefixes and scientific notation: 1 μ C = 1 x C( μ = “micro”) 1 nC = 1 x C(n = “nano”) 1 pC = 1 x C(p = “pico”)

Calculating Charge - Example If 16 million electrons are removed from a neutral sphere, what is the charge on the sphere in coulombs? ANSWER: 2.56 x C