Electric field

Electric field

• The space around a charged particle in which another charge experience a force.

• Here red circles shows the electric field. In this figure q is source charge and q₀ is test charge.
• The source of electric field is either a charge or a time varying magnetic field.
• If electric field (E) does not change with time, then it is said to be uniform electric field, otherwise it is non-uniform electric field.

Electric field intensity

• The electrostatic force per unit test charge is electric field intensity.

• Since test charge q₀ should be infinitesimally small.

Unit of electric field

• Unit of electric field is N / C or V / m
• Since force on q₀ due to q

• Therefore electric field

• Direction of unit charge is from q to q₀.

Electric field intensity due to many charges

• If  q₁,  q₂,  q₃, … are the points charges at the distance  r₁,  r₂,  r₃, … from the observation point respectively, then the total electric field at observation point will be

Electric field due to different charge distribution

Electric field due to line charge

• Linear charge density, λ = dq / dl
• Unit of λ is C / m

Electric field due to surface charge

• Surface charge density, σ = dq / ds
• Unit of σ is C / m²

Electric field due to volume charge

• Volume charge density, ρ = dq / dv
• Unit of ρ is C / m³

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