1. CHAPTER-22
Electric Field

2. Ch 22-2 Electric Field
Field: Region of space characterized by a physical property
Scalar property- scalar field;
vector property- vector field e.g. gravity
Electric Field characteristics:
Exerts force on a test charge
Electric field due to a charge and surrounds it
Direction of E ( given by arrow head): away from a positive charge and towards a negative charge

3. Ch 22-3 Electric Field Lines
Space around charge filled with lines of force or electric field lines
Direction of E at a point: along E-field lines or direction of the tangent to a curved field line
Magnitude of E at a point: Proportional to number of E-field lines per unit area , measured in a plane  to the lines. E.
Closer lines, stronger E field and farther the lines, the weaker is E field
Parallel E field lines means uniform E-field

4. Ch 22-4 Electric Field Due to a Point Charge
E=F/q0= [ kq0q/r2] /q0
E = [ kq/r2]
E-field due to sum of Charges:
Enet=Ei
=E1+E2+E3+….

5. Ch 22-4 Electric Field Due to a Point Charge
Field between two charges:
Net Zero Field Position:
For opposite charges , on the sides of the charges and nearer to weaker charge
For similar charges , between the charges and nearer to weaker charge

6. Ch 22-5 Electric Field Due to a Electric Dipole
Ed=2kqd/z3= 2kp/z3
where p is electric dipole moment p=qd
direction of p is taken from negative end to positive end of dipole

7. Ch 22-8 A Point Charge in an Electric Field
The electrostatic force F on a charge particle q in an external field E is in the direction of E for positive q charge and in opposite direction for negative charge
Particle acceleration
a=FE/m =qE/m

8. Ch 22-9 A Dipole in an Electric Field
Net torque on the dipole
= p xE = pEsin
Negative torque for clockwise rotation =- pEsin
Positive torque for counter-clockwise rotation =pEsin
Potential Energy U of a Dipole (U90=0)
UE =-WE=-90d= 90pEsin  d
UE=-p Ecos = -p.E
Umin=-pE (=0); Umax=+pE(=180);
WE=-UE=-(Uf-Ui)
Wappl = - WE

9. Thank you