This document provides an overview of electrostatics and how electric charges behave. It discusses that matter is made up of protons, neutrons, and electrons which can gain or lose electrons, becoming positively or negatively charged. It describes how like charges repel and unlike charges attract. Conductors, insulators, and semiconductors are introduced based on how easily their outer electrons can move. Methods of charging objects such as friction, conduction, induction, and more are explained. An electroscope is presented as a device to detect electric charge.

1. ELECTROSTATICS-PART 1
A POWERPOINT PRESENTATION
BY
BRAJESH KUMAR CHAUDHARY
FACULTY OF PHYSICS
RESONANCE EDUVENTURES PVT. LTD.
NAGPUR, INDIA.

2. ELECTROSTATICS
GIRL SAFELY CHARGED TO SEVERAL
HUNDRED THOUSAND VOLTS
GIRL IN GREAT DANGER AT
SEVERAL THOUSAND VOLTS
The branch of Physics which deals with electric effects of static
charge is called electrostatics.

3. ELECTRIC CHARGE

4. ELECTRIC CHARGE
Charge of a material body or particle is the property due to
which it produces & experiences electrical & magnetic effects.
Where do charges come from?
Matter is made up of atoms.
An atom consists of proton , neutron
& electron.
Proton = + ve charge
Electron= - ve charge
Neutron = no charge

5. Unlike
attract
-
+
Unlike
attract
+
- -
+
Like repel
Like repel
Charges are of two types. (a)Positive & (b) Negative. Like charges
(+ve &+ve or –ve & -ve) repel. Unlike charges (+ve & -ve) attract.

6. PROPERTIES OF CHARGE(Contd.)
CONSERVATION OF CHARGE
In an isolated system, sum of total charge remains constant
whatever change takes place in that system.
QUANTIZATION OF CHARGE
Charge of a particle or a body is always an integral multiple of a
fundamental unit of electric charge (e).
i.e.
19
, 1.6 10Q ne e C

7. PROPERTIES OF CHARGE(Contd.)
•Charge is always associated with mass. Charge can’t exist
without mass though mass can exist with charge.
•Charge is relativistically invariant.
•Charge is a scalar quantity. Its S.I. unit is Coulomb(C ).
•A Charge at rest produces only electric field around itself.
•A charge moving with uniform velocity produces electric &
magnetic field both.
•An accelerated charge emits electromagnetic radiations.

8. Numerical Problem #1
Estimate the number of electrons of
100 g of water. How much is the total
negative charge on the these
electrons.

9. CONDUCTOR,INSULATOR &
SEMICONDUCTOR
•In a conducting material, the
outer electrons of the atoms are
loosely bound and free to move
through the material.
•Semiconductors are between
conductors & insulators.
•In a insulating material, the
outer electrons of the atoms are
tightly bound and are not free
to move through the material.

10. CONDUCTOR,INSULATOR &
SEMICONDUCTOR
Property of material:
conductivity
1. Conductors transmit
charges readily.
2. Semiconductors are
intermediate; their
conductivity can depend on
impurities and can be
manipulated by external
voltages.
3. Insulators do not transmit
charge at all.

11. GROUNDING
An object is grounded when it is connected to the earth
through a connecting wire.
If a charged conductor is grounded, it will become neutral.
One symbol that is often used to show that
something is grounded is:

12. How does grounding occur?
When we touch a metal ball of
positive charge...
•Electrons flow from the earth
to the metal ball to neutralize
the metal ball.
•Metal ball becomes neutral.
+ +
+ ++

13. HOW DOES GROUNDING OCCURS?(Contd.)
–
–
–
––
Similarly, if the metal ball is of
negative charge...
Extra electrons flow from the metal
ball to the earth and the ball
becomes neutral.

14. METHODS OF CHARGING OF A BODY
Primarily a body can be charged by six methods
namely,
(a)By friction
(b)By Conduction
(c)By Induction
(d)By thermionic emission
(e)By Photoelectric effect
(f) By Field emission

15. CHARGING BY FRICTION
When insulators are rubbed together, one
gives up electrons and becomes positively
charged, while the other gains electrons
and becomes negatively charged.
Common examples of charging by friction:
• small shocks from a doorknob after
walking on carpet with rubber-soled shoes
•laundry from the dryer that clings
• balloon rubbed with hair sticks that to a
wall

16. CHARGING BY CONDUCTION
When a charged conductor makes contact with a neutral
conductor there is a transfer of charge.
Electrons are transferred
from the rod to the
ball, leaving them both
negatively charged.
Electrons are transferred from
the ball to the rod, leaving
them both positively charged

17. CHARGING BY INDUCTION
(a) (b)
© (d)
STEPS
(a) Bring a negatively charged rod near a
neutral conducting sphere.Due to
repulsion from rod free electrons of
conducting sphere move away from
rod. Thus a net positive charge
appears near rod and negative charge
away from rod.
(b) Now connect the sphere to ground
through a conducting wire from the
side where negative charges appear.
(c) Due to grounding the negative
charges flow to the ground, leaving
the sphere positively charged.
(d) Now, remove the rod. The positive
charges on the sphere arrange
themselves uniformly.

18. ELECTROSCOPE
Electroscope is a device which detects any charge on an
object.

19. ELECTROSCOPE
The electroscope can be charged either by conduction or by
induction.

20. ELECTROSCOPE(Contd.)
The charged electroscope can then be used to determine the
sign of an unknown charge.

21. ELECTROSCOPE(Contd.)
When the knob is charged, electric charge travels along the
rod and into the leaves. Then, the leaves repel each
other because they have the same charge.

22. CONCEPT QUESTION #1
+Q
If a positively charged object is placed near an uncharged
conductor, will it experience any force or not? If yes, then
attractive or repulsive? Will the answer change if charge in
question is negative?

23. CONCEPT QUESTION #2
Five Styrofoam balls A, B,C,D & E are used in an experiment and
following observations were made:
(a)A attracts B but repels C
(b)D attracts B but doesn’t have any effect on E
(c) A negatively charged rod attracts both A & E.
What can you say about charges on balls A,B,C,D &E?