Presentation on theme: "Electric Charge. Electricity Objects can be described by fundamental properties. Mass, velocity, energy, temperature, volume, etc.Mass, velocity, energy,"— Presentation transcript:
Electricity Objects can be described by fundamental properties. Mass, velocity, energy, temperature, volume, etc.Mass, velocity, energy, temperature, volume, etc. In ancient times is was observed that some items attracted small bits of material, especially when rubbed. Fossilized tree sap called amber had this property. Greek word for amber is elektronGreek word for amber is elektron The property was called electricity.
Static Electricity A person walking on a carpet picks up a negative charge. It follows that something else A) becomes equally negatively charged.A) becomes equally negatively charged. B) becomes equally positively charged.B) becomes equally positively charged. C) becomes charged, but the amount depends on the material.C) becomes charged, but the amount depends on the material. D) becomes magnetized.D) becomes magnetized.
Charge Electric charge is measured in coulombs (C). Electric charges come in small, but discrete units. Electron charge is 1.6 x 10 -19 CElectron charge is 1.6 x 10 -19 C Proton charge equal magnitude to the electron chargeProton charge equal magnitude to the electron charge Charges come in two types – positive and negative. Electron is negative, proton is positiveElectron is negative, proton is positive The sum of all charges is conserved.
Positive and Negative Rubbing a silk cloth on a glass rod charge both the cloth and rod. Extra electrons on cloth The combination is still electrically neutral.
Attract or Repel Two objects with the same sign charge will repel. Two objects with opposite sign charge will attract.
Polarized Positive and negative charges may not be uniform in an object. Charges can orient themselves to attract to another charge. This is called polarization. Allows neutral items to be attracted.
Charge Transfer Contact sequence from most positive to most negative: Rabbit Fur Glass Wool Silk Human Skin Cotton Wood Amber Rubber next Many items will transfer charge when they rub together. If one item gains positive charge, another item loses an equal amount to become negatively charged. Different items are more likely to gain positive or negative charge.