Transcript The Particle Model of Electricity and Atomic Structure

The Particle Model of Electricity
and Atomic Structure
Nature of Electricity: Part 2
Review
What is the model that we now accept for
explaining how charges work?
What charges attract each other?
What charges repel each other?
Particle Model of Electricity
Introduction:
Where have you
heard the word
‘Particle’ before?
How do you think that
applies to the Particle
Model of Electricity?
Atomic Model
Materials that posses charge are made up
of ATOMS.
The charge of an atom depends on the
number of electrons
(NEGATIVE) or
protons (POSTIVE).
Atomic Model
The nucleus cannot move from the atom,
therefore the protons (POSTIVE) cannot
move from the atom.
The nucleus has an overall POSTIVE
charge
The electrons (NEGATIVE) can move from
the atom.
Particle Theory of Electricity
1. Two types of subatomic particle are important
in the theory: electrons (-ve) and protons (+ve)
2. Charge cannot be created or destroyedcharge is CONSERVED
Particle Theory of Electricity
3.
Positive charges are fixed and
negative charges are free to
move.
4. A neutral object has equal
numbers of positive and negative
charge.
Part 3 of Particle Theory of
Electricity: Negatives can move
Part 4 of Particle Theory of
Electricity: Neutral Object
EQUAL AMOUNTS
OF BOTH POSTIVE
AND NEGATIVE
CHARGES MAKES
THIS OBJECT
NEUTRAL
Particle Theory of Electricity
5. A negative object has an excess of negative
charge. A positive object has a deficit of negative
charge.
6. Charge is shared by contact. Materials which
allow charge to move easily are called
conductors, and materials that do no allow
charge to move easily are called insulators.
7. Like charges repel; unlike charges attract.
Attraction of Neutral Objects to
Charged Objects
Neutral objects have a balance of both
positive and negative charges.
If they have that balance, why would they
be attracted to charged objects?
The difference lies in the difference
between INSULATORS and
CONDUCTORS
Attraction of a Neutral Object
(Insulator)
– Materials like paper,
which do not allow the
free movement of
electrons, are called
insulators.
– The charges on
insulators do not separate
readily but polarize
(align themselves). Since
opposite charges are
always closer to each
other, there is a net force
of attraction.
Explanation
If you bring a POSTIVELY charged ruler near
bits of paper (INSULATOR), the paper will be
attracted to the ruler.
If you bring a NEGATIVELY charged ruler near
bits of paper (INSULATOR), the paper will be
attracted to the ruler.
This is because the charges in the paper are
aligning opposite to what ever charge the ruler
has.
The charges stay together, but align depending
on what charge they are attracted to.
Attraction of a Neutral Object
(Conductor)
– Metals, allow the free
movement of negatives,
and are called
conductors.
– The charges on
conductors separate
readily, and are some
distance apart from each
other.
EXPLANATION
The pith ball (CONDUCTOR) is neutral and if
you bring a charged rod to it the pith ball will be
attracted to it.
The negatives (electrons) are free to move, so
they move towards the positive charge of the
rod.
If the pith ball and rod touch, the negatives on
the pith ball are attracted to the rod making the
rod less positive and the pith ball more negative.