1L 24 Electricity & Magnetism  static electricityWhy do I get a shock when I walk across the rug and touch the door knob?Why do socks stick to my pants in the dryer?Why does my hair stick to my comb, and I hear a crackling sound ?Why does a piece of plastic refuse to leave my hand when I peel it off a package?What is lightning?
2It’s the CHARGE! we know that stuff has MASS but . . . it also has CHARGE!the mass is what gives the gravitational forcethe charge is what gives us ELECTRICITY!You don’t always see the effects of charge because it’s stuck inside of atoms.
3What is in atoms?Atoms have a nucleus at its center and a bunch of electrons that move around itThe nucleus: two kinds of heavy particlesprotons – have a positive chargeneutrons – have no chargeThe electrons are very light particles that have a negative chargeSo charge comes in two flavors – plus and minuscharge is just another property like mass!
4Electric forces charges exert electric forces on other charges two positive charges repel each othertwo negative charges repel each othera positive and negative charge attract each other+++The repulsive electric force between 2 protons is1,000,000,000,000,000,000,000,000,000,000,000,000times stronger than the attractive gravitational force!
5How Strong is the Electric Force between two charges? It depends on how big the charges are, and how close they areThe bigger the charges, the bigger the forceThe closer the charges, the bigger the forceThis is known as Coulomb’s Law
6Conductors and Non- Conductors Metals (copper, aluminum, iron) are conductors of electricity that means that charge can move through themPlastics, wood, ceramics, and glass are non-conductors (or insulators) they do not let electricity flow through themYou should not stick a metal fork into an electrical outlet!You could stick a plastic fork into an outlet without electrocuting yourself, but don’t do it!
7What makes conductors conduct? Atoms have equal numbers of positive and negative charges, so that a chunk of stuff usually has no net charge the plusses and minuses cancel each other.However, when you put a bunch of metal atoms (like copper) together an amazing thing happens one electron from each atom forgets which atom it belongs to.All the homeless electrons are free to wander about inside the material
8Current– charges moving about If I connect a battery to the ends of thecopper bar the electrons in the copper willbe pulled toward the positive side of thebattery and will flow around and around. this is called current – flow of chargecopperAn electric circuit!Duracell+
9Seeing and hearing electricity! The capacitorkeeps charginguntil it reachesits limit.ChargestoragedeviceMany BatteriesCapacitor
10Fully loaded and ready to go! The sudden discharging of the capacitor is accompanied with a big spark and a bang man-made lightning!A spark occurs when there is enough energy released to cause the electrons in the air molecules to be ripped out of the molecules ionizationdangerfullycharged
11Non-conductors can be charged too! Even though non-conductors do not have free electrons meandering about, they can be charged by frictionWhen you move your comb through your hair, the friction (rubbing) between the comb and hair can pull some of the electrons out of your hair and onto the combas a result your comb ends up with a net negative charge and attracts your hair which is now positive.
12Charging by frictionIf you rub plastic with cat’s fur, electrons are rubbed onto the plastic making it negativeif you rub glass with silk, electrons are rubbed off the glass making it positivethe charge can be transferred to other objects.
13Attracting uncharged objects +A negatively chargedrod will push theelectrons to the farside leaving the nearside positive.The force is attractivebecause the positivecharges are closer tothe rod than the negativechargesunchargedmetal sphere
14You can bend water with charge! charged rodThe water moleculehas a positive end anda negative end.When a negative rod isbrought near the streamof water, all the positiveends of the water mole-cules turn to the rightand are attracted to thenegative rod.stream of water
15We can cause the 2 x 4 to move The Magic Wand2 x 4We can cause the 2 x 4 to movewith electric forces