This document discusses electric charges and static electricity. It explains that atoms are made up of protons, neutrons, and electrons. The proton has a positive charge, the electron has a negative charge, and the neutron is neutral. It also discusses how charges behave, with like charges repelling and unlike charges attracting. Static electricity is generated through friction, such as when a polythene rod is rubbed with wool, transferring electrons from the wool to the rod. Conductors, insulators, and semiconductors are compared in terms of how they allow electrons to pass through. Earthing and electrostatic induction are also summarized.

1. Electric Charge

2. Objective
• To understand about electric charges & its
transfer by friction

3. Electricity
Electricity
Static electricityCurrent electricity

4. Static electricity
• Also known as electrostatic
charges
• Generated due to friction.

5. Where do charges come
from?
Matter is made up of atoms.
+
+
+
–
––
+
–
Proton (positive charge)
neutron (neutral)
electron (negative charge)
atom nucleus

6. Charge
• The electron is negatively charged.
• The proton is positively charged.
• The neutron has no charge, it is neutral.

7. If electrons = protons neutral
Where do charges come
from??
If electrons > protons  gaining electrons, negative
charge
If electrons < protons  losing electrons, positive charge

8. How do charges behave?
• Like charges repel; unlike charges
attracts.
• A charged object may even attract a
neutral one.

9. Examples
• When a polythene rod is rubbed with a
woolen cloth, electrons transfers from the
wool to polythene. So the polythene get a
net negative charge & wool gets positive
charge

10. Conductors , Insulators &
semiconductors

11. CONDUCTORS INSULATORS SEMICONDUCTORS
They are
materials that
allows heat &
electrons to pass
through it
They don’t allow
heat & electrons
to pass through it
They are poor
conductors when
cold ,but much
better conductor
when warm
Electrons are
loosely held in
conductors
Electrons are
tightly packed in
insulators
They are ‘in-
between’
materials
Eg: metals Eg: plastic, wood Eg: silicon,
germanium

12. Earthing
• If charges build upon materials, electrons
may be pulled through the air and causes
spark
• To prevent any danger due to this spark,
the object can be earthed
• Earthing means the object is connected to
the ground by a conducting materials so
that unwanted charges flows away.

13. Electrostatic induction

14. 1)Charging a Two-Sphere System Using a
Negatively Charged Object

15. 2)Charging a Two-Sphere System Using a Positively
Charged Object

16. 3)Charging(positively) a single sphere by induction

17. 4)Charging(negatively) a single sphere by induction

18. Electrostatic induction
• The production of a charge in an
uncharged body by bringing a
charged object close to it is known as
electrostatic induction.
• The charges that appear on the
uncharged materials are known as
induced charges

19. Electric field

21. • The region around the electric charges
where another charge when placed will
experience a force of attraction or
repulsion is called an electric field
• the direction of electric field is from the
positive charge to the negative charge
• Electric field is represented by imaginary
lines called electric field lines.

22. Home work
• Write any 3 Dangers of static electricity