The branch of Physics which deals with the properties of charges at rest is called electrostatics
Electrical conductors and insulators
An electrical conductor is
a material through which
electric current flows
easily.
All metals are
conductors.
Electrical insulators have
a very high resistance to
the flow of electric
current.
Complete the table below:
copper
rubber
steel
mercury
paper
plastic
diamond
graphite
conductor
1
insulator
2
conductor
3
conductor
insulator
4
insulator
5
insulator
6
conductor
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Electric charge
Electric charge can be either
positive or negative.
In an atom an electron has a
negative charge that is of the same
size as the positive charge of a
proton.
Neutrons have no electric charge.
As an atom has the same number
of electrons as protons it is
uncharged.
TRIPLE ONLY
Static and current electricity
Static electricity describes the situation when electric
charges remain stationary.
This occurs best with insulators.
An electric current occurs when electric charges are
moving from one place to another.
This occurs best with conductors.
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Charging materials using friction
When certain insulating materials are rubbed against each other they become electrically charged.
Electrons are rubbed off one material onto the other.
The material that gains electrons becomes negatively charged.
The material that loses electrons is left with an equal positive charge.
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Force and charge
When a charged object is brought close to an
uncharged one the two objects attract each other.
The charged comb
attracts the column of
water
Charged balloon
attracted to a wall
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Attraction and repulsion
Two bodies that carry different
types of charge attract.
Two bodies that carry the same
type of charge repel.
The law of charges:
LIKE CHARGES REPEL, UNLIKE
ATTRACT.
This boy’s hair has all the
same type of charge!
TRIPLE ONLY
TRIPLE ONLY
Choose appropriate words to fill in the gaps below:
charge remains
Static electricity occurs when electric ________
stationary
____________
on an object.
insulating
rubbing
An __________
object can be charged by __________
it with
electrons and becomes
another insulator. One of them gains ________
positively
negatively charged. The other becomes equally __________
charged.
repel
The law of charges states that; ‘like charges _______,
unlike
attract
_________’.
WORD SELECTION:
attract
insulating electrons
rubbing
positively
repel
charge
stationary
COULOMB’S LAW
CONSTANT
CONDITION
Point charges:
The charges whose sizes are very small as compared to the distance between them are called point
charges.
Dielectric
ELECTRIC FIELD
The space or region around any charge, in which it exerts forces of
attraction or repulsion on other charges, is called its electric field.
PROPERTIES OF ELECTRIC LINES OF FORCE
Electric field lines originate from positive charges and end on negative
charges.
The tangent to a field line at any point gives the direction of the electric
field intensity at that point.
The lines are closer where the field is strong, the lines are farther apart
where the field is weak.
No two lines cross each other.
ELECTRIC FIELD INTENSITY