The Particle Model of Electricity The Particle Model of Electricity and Atomic Structureand Atomic Structure

Nature of Electricity: Part 2Nature of Electricity: Part 2

ReviewReview

What is the model that we now accept for What is the model that we now accept for explaining how charges work?explaining how charges work?

What charges attract each other?What charges attract each other?

What charges repel each other?What charges repel each other?

Particle Model of ElectricityParticle Model of Electricity

Introduction:Introduction:

Where have you Where have you heard the word heard the word ‘Particle’ before?‘Particle’ before?

How do you think that How do you think that applies to the Particle applies to the Particle Model of Electricity? Model of Electricity?

Atomic ModelAtomic Model

Materials that posses charge are made up Materials that posses charge are made up of ATOMS.of ATOMS.

The charge of an atom depends on the The charge of an atom depends on the number of electronsnumber of electrons

(NEGATIVE) or (NEGATIVE) or

protons (POSTIVE).protons (POSTIVE).

Atomic ModelAtomic Model

The nucleus cannot move from the atom, The nucleus cannot move from the atom, therefore the protons (POSTIVE) cannot therefore the protons (POSTIVE) cannot move from the atom. move from the atom.

The nucleus has an overall POSTIVE The nucleus has an overall POSTIVE chargecharge

The electrons (NEGATIVE) can move from The electrons (NEGATIVE) can move from the atom.the atom.

Particle Theory of ElectricityParticle Theory of Electricity

1. Two types of subatomic particle are important 1. Two types of subatomic particle are important in the theory: in the theory: electronselectrons (-ve) (-ve) and and protonsprotons (+ve) (+ve)

2. Charge cannot be created or destroyed- 2. Charge cannot be created or destroyed- charge is CONSERVEDcharge is CONSERVED

Particle Theory of ElectricityParticle Theory of Electricity

33. Positive charges are fixed and . Positive charges are fixed and negative charges are free to negative charges are free to move. move.

4. A neutral object has equal 4. A neutral object has equal numbers of positive and negative numbers of positive and negative charge.charge.

Part 3 of Particle Theory of Part 3 of Particle Theory of Electricity: Negatives can move Electricity: Negatives can move

Part 4 of Particle Theory of Part 4 of Particle Theory of Electricity: Neutral Object Electricity: Neutral Object

EQUAL AMOUNTS EQUAL AMOUNTS OF BOTH POSTIVE OF BOTH POSTIVE AND NEGATIVE AND NEGATIVE CHARGES MAKES CHARGES MAKES THIS OBJECT THIS OBJECT NEUTRALNEUTRAL

Particle Theory of Electricity Particle Theory of Electricity

5. A negative object has an excess of negative 5. A negative object has an excess of negative charge. A positive object has a deficit of charge. A positive object has a deficit of negative charge. negative charge.

6. Charge is shared by contact. Materials which 6. Charge is shared by contact. Materials which allow charge to move easily are called allow charge to move easily are called conductors, and materials that do no allow conductors, and materials that do no allow charge to move easily are called insulators. charge to move easily are called insulators.

7. Like charges repel; unlike charges attract. 7. Like charges repel; unlike charges attract.

Attraction of Neutral Objects to Attraction of Neutral Objects to Charged Objects Charged Objects

Neutral objects have a balance of both Neutral objects have a balance of both positive and negative charges.positive and negative charges.

If they have that balance, why would they If they have that balance, why would they be attracted to charged objects? be attracted to charged objects?

The difference lies in the difference The difference lies in the difference between INSULATORS and between INSULATORS and CONDUCTORS CONDUCTORS

– Materials like paper, Materials like paper, which do not allow the which do not allow the free movement of free movement of electrons, are called electrons, are called insulators. insulators.

– The charges on The charges on insulators do not separate insulators do not separate readily but polarize readily but polarize (align themselves). Since (align themselves). Since opposite charges are opposite charges are always closer to each always closer to each other, there is a net force other, there is a net force of attraction.of attraction.

Attraction of a Neutral Object Attraction of a Neutral Object (Insulator)(Insulator)

ExplanationExplanation

If you bring a POSTIVELY charged ruler near If you bring a POSTIVELY charged ruler near bits of paper (INSULATOR), the paper will be bits of paper (INSULATOR), the paper will be attracted to the ruler. attracted to the ruler. If you bring a NEGATIVELY charged ruler near If you bring a NEGATIVELY charged ruler near bits of paper (INSULATOR), the paper will be bits of paper (INSULATOR), the paper will be attracted to the ruler.attracted to the ruler.This is because the charges in the paper are This is because the charges in the paper are aligning opposite to what ever charge the ruler aligning opposite to what ever charge the ruler has. has. The charges stay together, but align depending The charges stay together, but align depending on what charge they are attracted to. on what charge they are attracted to.

– Metals, allow the free Metals, allow the free movement of negatives, movement of negatives, and are called and are called conductors. conductors.

– The charges on The charges on conductors separate conductors separate readily, and are some readily, and are some distance apart from each distance apart from each other. other.

Attraction of a Neutral Object Attraction of a Neutral Object (Conductor)(Conductor)

EXPLANATIONEXPLANATION

The pith ball (CONDUCTOR) is neutral and if The pith ball (CONDUCTOR) is neutral and if you bring a charged rod to it the pith ball will be you bring a charged rod to it the pith ball will be attracted to it.attracted to it.

The negatives (electrons) are free to move, so The negatives (electrons) are free to move, so they move towards the positive charge of the they move towards the positive charge of the rod. rod.

If the pith ball and rod touch, the negatives on If the pith ball and rod touch, the negatives on the pith ball are attracted to the rod making the the pith ball are attracted to the rod making the rod less positive and the pith ball more negative. rod less positive and the pith ball more negative.