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