ELECTRICITYELECTRICITY

1. Electric Charge1. Electric Charge Atoms are made up of 3 particlesAtoms are made up of 3 particles

– NeutronsNeutrons have a have a neutralneutral charge. charge.– ProtonsProtons have a have a positivepositive charge. charge.– ElectronsElectrons have a have a negativenegative charge.charge.

An atom is electrically neutral if An atom is electrically neutral if the number of electrons the number of electrons EQUALSEQUALS the number of protonsthe number of protons

However, atoms sometimes However, atoms sometimes LOSE or GAIN electrons.LOSE or GAIN electrons.

When excess (or extra) electrons When excess (or extra) electrons are stored, an overall NEGATIVE are stored, an overall NEGATIVE (-) charge is achieved(-) charge is achieved

ChargesCharges Handy rule : Opposites attractHandy rule : Opposites attract

And likes repel

2. Electric fields2. Electric fields

Every electric charge is surrounded by an Every electric charge is surrounded by an electric field which can exert a force on electric field which can exert a force on objects which come into it.objects which come into it.

These fields can push or pull over distances

2 types of electricity2 types of electricityStatic electricityStatic electricityElectric currentElectric current

Static electricityStatic electricity is an accumulation is an accumulation of electric charges on an object.of electric charges on an object.

- transferred

Negative ChargeNeutral Charge

Charging objectsCharging objects

Objects can become charged by a variety of Objects can become charged by a variety of methodsmethods

2 ways are 2 ways are – Charging by CONTACTCharging by CONTACT– Charging by INDUCTIONCharging by INDUCTION

Charging by ContactCharging by Contact Objects touch or rub Objects touch or rub

against each other against each other (contact)(contact) and charge is and charge is transferredtransferred

Charging by InductionCharging by Induction

Occurs when a Occurs when a charged object is charged object is brought near a brought near a neutral object. The neutral object. The charges in the charges in the neutral object neutral object rearrange rearrange themselves and themselves and present the illusion present the illusion of a charge.of a charge.

Once objects are charged, they can then Once objects are charged, they can then transfer their charge…sometimes, suddenly, in transfer their charge…sometimes, suddenly, in what is called a STATIC DISCHARGE.what is called a STATIC DISCHARGE.

Electric CurrentElectric Current

Is the flow of electrons through a conductor, Is the flow of electrons through a conductor, such as a copper wiresuch as a copper wire

Conductors and InsulatorsConductors and InsulatorsConductors = materials which allow excess electrons to easily move through them.

Examples : metals, water

The Earth also functions as a conductor.

Conductors and InsulatorsConductors and Insulators

Insulator = a material that doesn’t allow electrons to move through it easily

Examples : plastic around wires, wood doors, fiberglass, rubbers

Notice what the handles are made of. Why?

ElectroscopeElectroscope

A device made up of A device made up of two thin metal leaves two thin metal leaves attached to a attached to a knobbed metal rod. knobbed metal rod. The leaves can move The leaves can move and hang straight and hang straight down when not down when not charged. This device charged. This device is used to detect is used to detect electric charges.electric charges.

LightningLarge static discharge

Air masses move and swirl

Top +Bottom -

Negative charge induces a + chargeon ground (repel e-)

Bottom accumulates enough -

Electrons in cloud attractedto ground

When electrons get close to ground

Positive charges are attracted

Connection made

= lightning

Electric charges move through air collide with atoms/molecules

Collisions cause atoms/molecules to emit light

Powerful sound waves

Electrons are ripped off atoms in the airProduce great amounts of heat

Warms surrounding air to 25,000 C (2.5x hotter than Sun surface)

Heat causes air in path to expand rapidly sound waves = Thunder

Earth is a large neutral object

Connection (conductor) will transfer any excess electric charge

“Grounding” – the act of making a connection for an electric charge to

go to the Earth(Lightning rods)