Qualitatively, Electric Charge may be defined as that property of matter that leads to attraction and repulsion interaction.

There 2 types of electric charge: Positive Charge and Negative Charge.

All objects possess electric charge. An object or particle is considered positively charged if its total charge is positive. An object or particle is considered negatively charged if its total charge is negative. An electrically neutral object or particle has a total charge of zero.

Unit: 1 coulomb = 1 C

q=qpositive+qnegative

e=1.6021019C

qelectron=e=1.6021019 C

melectron=9.1091031 kg

q proton=+e=+1.6021019C

mproton=1.6731027 kg

qneutron=0Cmneutron=1.67510

27 kg

Each electric charge produces an Electric Field in the surrounding space.

E= 140

qr2

E = electric field at a pt. a distance r from charge qq = charge producing electric field Er = distance from charge q0 = permittivity of free space = 8.854 x 10-12 C2/Nm

Unit of E: 1 N/m

The electric field is a vector quantity and is, by convention, considered to be directed away from the positive charge and towards the negative charge.

If there are 2 or more charges present in the area, then the electric field at a particular point is the vector sum of the electric fields produced by charges.

Etotal= Ei= E1+ E2+E3+...

When a charge q1 is placed in an electric field produced by another charge q2, then q1 experiences a force due to the electric field of q2. Similarly, the electric field of q1 will exert a force on q2. Such a force is given by Coulomb's Law.

r = distance betweenq1 and q2

The direction of this interaction force is given by:Similar charges repel each other while opposite charges attract each other.

F=F12=F21=1

4 0

q1 q2r2

In terms of the electric field, the force F0 exerted on charge q0 by an electric field E (produced by another charge q) is given by

E= Fq0

Just like total electric field, the total force experienced by a charge is the vector sum of the forces due to the electric fields of other charges in the area.

F total= F i= F1+ F2+F3+...

An electric field that is constant (in both magnitude and direction) not only with respect to time but to position as well is referred to as a Uniform Electric Field.

E= Fq0=constant

F=E q0=constant=m a

Electric force is a conservative force. The work done by an electric force does not depend on the path taken and is stored in the form of Electric Potential Energy.

For 2 charges separated by distance r,

U= 14 0

q1 q2r

Hence the potential energy between 2 charges is

dW=Fd x=Fcosdx=Fcos0 dr

= 140

q1 q2r2

dr

W= 14 0

q1 q2r i

14 0

q1 q2r f

U = + = similar charges = repulsionU = - = opposite charges = attraction

For a charge in a uniform electric field,

E=Fq=constant F=Eq=constant

dW=Fd y=F cosdy=Eqcos 0dyW=Eq( y f yi)

U=Eqy

Hence for uniform electric field, the potential energy is

Just as the electric field is force per unit charge, electric potential energy may also be described in terms of energy per unit charge. This quantity is referred to as Electric Potential.(unit: 1 J/C = 1 volt = 1 V)

V= Uq0

V single change=1

4 0qr

V uniform electric field=EyThe electric potential for uniform electric field gives us another unit for the electric field: 1 V/m = 1 N/C

Comparing the electric potential between 2 points gives us the Electric Potential Difference or Voltage.

V=V aV b=voltage