Electrostatics is a branch of physics that studies electric charges at rest. It was discovered in 600 BC by Thales that certain materials like amber could attract dust when rubbed. In the 16th century, William Gilbert discovered that other materials like glass and ebonite showed the same phenomenon. Benjamin Franklin later experimentally studied the electrification of objects. Coulomb's law quantifies the electrostatic force of attraction or repulsion between electric charges. Electric field is produced by electric charges and exerts force on other charges. Gauss' law relates the electric flux through a closed surface to the net electric charge within the surface.

1. Chapter
Electrostatics

2. Electrostatics is a branch of Physics that studies electric
charges at rest.
History:-
600 B.C Thales discovered ----- Fossil material(Amber)
when rubbed with fur , attracts dust, pieces of papers
16th centaury A.D. William Gilbert discovered ----- not only
amber & wool but glass, ebonite etc when rubbed with
suitable material shows same phenomenon
 Benjamin Franklin Experiment:-

3. Electrification Of Object

7. Forces Between the charges

8. Coulomb’s Law

10. 1 Coulomb

11. Dielectric Constant
k= 1 ………………….. for air & Vacuum
K > 1 …………………. For other medium

12. Coulomb’s Law in Vector Form:-
LIKE CHARGES

14. F12 = - F21
r12 = - r21

15. UNLIKE CHARGES

16. r12 = - r21
F12 = - F21

18. Similarly, F14, F15, …………can be written

19. Electric Field
 Electric Charge produces electric field in its surrounding
When another charge is brought in this region it
experience an electric force
E = F/q0

20. Electric Intensity
Dimension [M1L1 T-3 A-1]

21. Electric Intensity due to Point Charge
Vector Form Of E

22. Line Charge Distribution
Unit :- Coulomb/meter

24. Electric Lines of Force:
Michael Faraday (1791-1867) :- Introduced the concept of
lines of force
Definition:-
An electric line of force is an imaginary curve drawn in such a
way that the tangent at any given point on this curve gives the
direction of the electric field at that point.
B

25. Properties of Electric Lines of Force

26. Electric Flux
Number of lines of force = (E).(Area)
Φ = E• A

27. S
Number of lines of force = (E).(Area)
Φ = E• A
dΦE = E• ds = Eds Cosθ
S.I Unit :- N m2 / C Or V m

28. Gauss' Law
The total electric flux through any closed surface equals the
net charge enclosed by the surface divided by ε0
Gauss' law is analogous to Coulomb’s law in the sense that it
too expresses the relationship between electric field and
electric charge.
Gauss' law provides equivalent method for finding electric
intensity