3.
Electrostatic
1. Static Electricity electrical charge
that is at rest or not moving.
2. Electrostatic is the study of static
electricity.
3. There are 2 types of static electric
charge:
Positive
charges
(+)
Consists of Protons
(that cannot move)
Negative
Charges
(-)
Consists of electrons,
Electron can move and electron
transfer happens when two
different materials are
rubbed together.
Static electric charges can be produced
on a neutral object by rubbing it with a
different material like a woollen or silk
cloth.
When two different materials are
rubbed, electron transfer occurs.
One of the material receives electrons
while the other loses electrons.
ruler
+ - +- + 3 protons (+)
3 electrons (-)
Neutral
- +
+ - +
Woolen cloth
3 protons (+)
3 electrons (-)
Neutral
Before rubbing
Charging object by rubbing
3 protons (+)
5 electrons (-)
Negatively charged
-+ - +- + -Electron
transfer
+
+ +
3 protons (+)
1 electron (-)
Positively charged
After rubbing
A Neutral material has the same number of positive
and negative charges.
+++ +++
-----Neutral material
When two different materials are rubbed together,
electrons will be transferred from one material to
another.
Material that loses electrons will become positively
charged.
+ + + + + +
- - - - Positively charged
When two different materials are rubbed together,
electrons will be transferred from one material to
another.
Material that receives electrons will become
negatively charged
+ + + + + +
-- - - - - - - Negatively charged
Characteristics of static electric
charges
4. Positive charges and negative charges
have the ability to ATTRACT or REPEL
other charges.
5. Charges of the same type (like
charges) REPEL one another.
+
Repel one another
6. Charges of different types (unlike
charges) ATTRACT one another.
Attract one another
7.The repulsive force and attractive force that
exist between electrical charges is
called Electrostatic Force (caused by Static
Electric charges)
8. Producing and detecting electrical charges
i.
Electrical charges are produced by friction.
ii.
Friction can causes some electrical charges
(electrons) to be transferred .
iii. Plastic substances such as polythene and
cellulose acetate are easily charged when rubbed
with some wool.
iv. An ELECTROSCOPE is a device used to detect
the electrical charges present in a material.
Metal cap /
Metal disc
Insulator
Glass wall
Metal rod
Metal plate
Metal glass container
Gold leaf/
Gold foil
To earth
Insulator base
Fig. of an Electroscope- a device used to detect the
electrical charges present in a material.
9. Before we used the electroscope, it is
must be earthed by touching the metal
disc with a finger.
10.This is intended to neutralise the
electroscope.
11.When a charged material is brought near
the metal disc of the electroscope, its
gold foil/leaf will diverge.
When a material that is not charged (neutral) is brought near
the metal disc of the electroscope, its gold foil/leaf does not diverge.
Metal disc (neutral)
Uncharged material
Gold foil/leaf does not diverge
When a charged material is brought near the metal disc of
the electroscope, its gold foil/leaf will diverge.
Metal disc (neutral)
++
charged material
++
-+
++
-
Gold foil/leaf diverges
+ + +
++
++
++
+
What happen to gold foil?
+ + +
----
What happen to gold foil?
Phenomenon related to static electric charges in daily life
Friction between two materials produces electric charges.
Because of this, Electric charges can be produced anywhere.
Example :
a, Occurrence of lightning
Clouds acquire electrical charges when water vapour in it rubs with air.
---------Charges jump from cloud to the
Earths surface because of
Electrostatic attractive force,
A lightning is produced.
+ + + + +
+
Earths surface
Most Cloud in the air contain
More negative charges.
When clouds that have
negative charges move closer to
the Earths surface,
These clouds will cause materials
On earth to become positively.
Lightning can also occur when two groups of clouds of
opposing charges come close to one another.
- - - - - - - - - - - - -
+ + + +
+ +
+ + + + +
Electric charges will jump from one group of clouds to another,
Hence, lightning is produced.
b, Spark plug
A spray of sparks is
produced when a car engine
is started.
Electric charges jump
across spark space on the
plug to produce sparks.
These sparks cause fuel to
burn to produce energy.
Electronic gas lighter
