Electric Charge

Atoms

•Small particles of matter•Composed of 3 smaller

particles:•Protons = positive (+) charge•Electrons = negative (-) charge•Neutrons = no charge (neutral)

Nucleus (protons & Neutrons) Electrons

Atom

Electric Charge

• Property causing particles to attract or repel each other

• Transfer of electrons causes objects to become charged– gain electrons = negative charge– lose electrons = positive charge

– Unit is Coulomb: amount of charge carried by 6.25 x 1018

electrons

Electric Force: attraction or repulsion between charges

Like charges Repel Opposite charges attract

Electric Field• Effect electric charge has on

other charges around it• Strength depends on:• 1. Amount of charge it produces• 2. Distance from the charge

– STRONGER WHEN CLOSER

– Viewing charges

+ -

Electric Field

Points outwardPoints inward

Static Electricity

• How charges build up and transfer between objects

• 3 Ways to transfer charge• 1. Friction• 2.Contact• 3.Induction

Charging By Friction• Loosely held electrons from one

object are transferred to another object by rubbing together– Ex: Rubbing balloon against clothes– Walking across a carpet

Charging by contact

• Object with excess electrons touches a neutral object, electrons are passed to neutral object– Van de Graaff generator:

charged sphere. Hair gains electrons

Charging by Induction

• Transfer of charge without contact

– Reaching for a doorknob after walking across carpet

– Viewing induction one sphere– Viewing induction two spheres

Static Discharge

• Sudden release of built up charge– Path must form

between objects• Examples:

– Shock touching doorknob

– Lightning (large discharge)

– How lightning forms

Electroscope•Device that detects electric charge–Leaves separate if charged