# Outline Origin of Electricity Electric Charge Early Theories

• Slides: 33

Outline Origin of Electricity Electric Charge Early Theories on Charges Quantization Of Charge Conservation of Electric Charge The Triboelectric Series Conductors and Insulators Process of Charging

Electricity filament

Switch 1 Switch 2 Lamp 1 Lamp 2

D. C. Electricity Direct Current A. C. Alternating Current

Static electricity

Static Electricity when a material has an excess or a lack of electrons.

Conductor Something that allows thermal energy to pass easily Metal Water

Insulator Something that does NOT allow thermal energy to pass easily

semi-Conductor

The Origin of Electricity Lode stone – magnetized iron core. Amber – a translucent yellowish- brown fossil resin.

The first recorded investigator of such ability of amber was Thales of Miletus ( as early as 600 B. C. ) – one of the seven wise men of ancient Greece, William Gilbert ( 1600) – found out that many other substances when rubbed against another substance have this ability of amber. He called these substances electrics which comes from the Greek word elektron meaning “amber”. It was shown that every object acquires this ability to attract small pieces of matter after it was rubbed against another.

Electric Charge “When amber rubbed with wool, the amber could then attract other objects”. We say that amber has acquired a net electric charge or has become charged. “When you scuff your shoes across a nylon carpet, you become electrically charged, and you can charge a comb by passing it through dry hair”.

Electric Charge Glass rod rubbed with silk Plastic rod rubbed with fur There are two kinds of electric charge: positive and negative. The figure demonstrates that charge with the same electrical sign repel each other, and charges with opposite electrical signs attract each other. In the rubbing process, small amount of positive charge is transferred from the silk cloth to the glass rod, so the original neutral rod is now positively charged. The opposite happens when a plastic rod is rubbed with fur. In the above, neutral means that the total number of positive charge is same as the total number of negative charge in the object.

Early Theories on Charges One fluid theory by Benjamin Franklin. According to this theory, all bodies possess a certain amount of “electric fluid” needed to keep them uncharged. When two bodies are rubbed together, one of the bodies get some of this fluid from the other body. The body that loses some of the fluid becomes negatively charged; the one that gains the fluid become positively charged. Two - fluid theory by Charles Du Fay – “all bodies contain equal amount of two kinds of fluid. When two bodies are rubbed together, one of these fluids spreads over one body making it positively charged, while the other kind of fluid spreads over the other body, making it negative charged.

Dielectric theory of James Clerk Maxwell and Michael Faraday – consider charges as a form of strain in the hypothetical ether surrounding a body. To charge a body is to strain the ether and to discharge it is to remove this strain.

The Atomic Structure The modern theory of electric charges is the electron theory. It explains the existence of charges by the structure of atom.

Atomic Structure

The number of protons and electrons are equal and hence the atom is neutral. An atom may gain or loses electrons under some circumtances. If the atom gains electron, it become negatively charged. If it loses electrons, it becomes positively charged. The SI unit of charge is coulomb, C. The charge of an electron (-e) is -1. 6 x 10 -19 C. The charge of proton (+e) is +1. 6 x 10 -19 C.

Important Facts About Proton, Neutron, and Electron Location Mass Charge Proton Inside Nucleus 1. 6725 x 10 -27 kg +1. 6 x 10 -19 C Neutron Inside Nucleus 1. 6749 x 10 -27 kg None Electron Around Nucleus 9. 1095 x 10 -31 kg -1. 6 x 10 -19 C

Answer : 1. How many electrons must be removed from an object for it to have a charge of 1. 0 C?

Switch 1 Switch 2 Lamp 1 Lamp 2

Electricity filament

Electricity - electrons moving through a metal wire.

Atomic Absorption

Atomic Emission Magic is technology that is not understood.

Electrical Energy - is energy resulting from the force between two objects having different voltages.

Electrical Energy - is the force of moving electrons.

Circuits Series Parallel

Static electricity 3/12/2021 31

Static electricity 3/12/2021 32

Electricity filament 3/12/2021 33