Electric Charges and Currents
Electric Charge
• 3 parts of an atom– Proton ( + )– Neutron ( o )– Electron ( - )
• Like charges repel• Different charges
attract
Electric Field
• An electric field extends outward through space around every charged particle
• It is strongest near the charged particle
Static Electricity
• Objects become charged when they gain or lose electrons
• Friction occurs when two objects are rubbed against each other
• Static electricity is the buildup of electric charges on an object
Conductors/Insulators
• Conductors permit electric charges to flow freely- examples: metals, Earth
• Insulators do not allow electric charges to flow freely
• - examples: rubber, glass, wood, plastic, air
Lightning
• Lightning forms when there is a discharge of static electricity
• Bolt travels from negative charges to positive charges
• Elect. Pot. Difference is the amount of work required to move a charge (Volts)
Batteries
• A battery is a device that produces electricity by converting chemical energy into electrical energy
• Batteries can be either dry cell or wet cell
Thermocouples
• A thermocouple is a device that produces electrical energy from heat energy
• Used in car engines, ovens, and gas furnaces
Electric Circuits
• A circuit provides a complete, closed pathway in which electricity can flow
• Two types (series/parallel)
• Our homes have parallel circuits - if one light goes out, the others stay on
Two Types of Circuits
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Electrical Safety
• Houses are protected against fires by fuses and circuit breakers
• Know the 6 electric safety rules on pages 37-38