Presentation on theme: "Static Electricity Static charges collect on surfaces and remain there until given a path to escape."— Presentation transcript:
1Static ElectricityStatic charges collect on surfaces and remain there until given a path to escape.
2What is Static Electricity? Static electricity is the build up of electric charge on the surface of objects.The static charges remain on an object until they are given a path to escape.
3How do objects get Static Electricity? All matter is made of atoms that contain charged particles – electrons and protonsThe protons are held tightly in the nucleus (with the neutrons) but the electrons are spinning around the nucleus in orbits
4How do objects get Static Electricity? The electrons can leave the atom and go to another atom, leaving one atom positively charged and the other negatively charged.
6Protons cannot move!!Static electricity is caused by the movement of the electrons.The protons cannot move.An object becomes positively charged when some electrons are removed!
7How do objects get Static Electricity? Usually the number of electrons and protons is the same so that the object is neutral (without charge)Electrons can be transferred from one object to another by friction
8How do objects get Static Electricity? When two objects of different materials are rubbed together, one always becomes positively charged and the other becomes negatively charged
9Electron AffinityElectron affinity refers to the tendency of a material to hold onto electrons.Different materials have different abilities to hold onto electrons
10Electron AffinityIn some materials, like acetate, the atoms do not have a strong hold on the electrons, and will lose some electrons when rubbed with a material with a stronger electron affinity
11Electron AffinityIn some materials, like gold, the electrons are held very tightly, and will steal electrons from other materials with a weaker hold on electrons.Goldacetate
12Electrostatic SeriesA list of some materials listed in order of their electron affinity.The materials at the top of the list have a lower electron affinity than the materials below
13Electrostatic SeriesThis means that when two materials are rubbed together, the one that is listed above the other will lose some electrons and become positively chargedThe material that is below the other will gain those electrons and become negatively charged
15Predict the charge Glass and nylon Wood and nylon Steel and Teflon You pet a catSilk and cottonGlass and cotton
16Important fact: no electrons are lost Important fact: no electrons are lost! They are only transferred to another material
17The Laws of Electric Charges Objects with a like charge will repelObjects with an unlike charge will attractNeutral objects are attracted to charged objects_ _ _ _ _ _ _ __ _ _ _ _ _ _ __ _ _ _ _ _ _ _
18How will these two react? _ _ _ _ _ _ _ __ _ _ _ _ _ _ _
24Why do objects with static charged stick together? When objects become charged they are attracted to neutral objects and to objects with the opposite charge
25The rubber balloon was rubbed onto the woolen sweater The balloon took the electrons from the sweater since rubberhas a higher electron affinity than woolThe negatively charged balloon sticks to the positivelycharged sweater. The wall is neutral – equal numberof electrons and protons
26The negatively charged balloon is brought close to the wall The negatively charged balloon is brought close to the wall. The electrons in the wall are repelled by the excess electrons in the balloon and they move away from the balloon leaving the part of the wall closest to the balloon positively charged. The positive wall and the negative balloon are attracted to each other and they stick.
27Induced charge separation Occurs when a neutral object comes close to a charged object.The electrons in the neutral object move towards a positively charged object (attracted)Or the electrons move away from a negatively charged object (repelled)This leaves the side of the neutral object with the opposite charge to the charged object
28Why dust sticks to your T.V. +++-+-++--+Neutraldust particleT.V.