When a point light positive charge is placed in a certain area, the path it follows due to electric force is called an electric field line. Electric field lines spread from positive charges.
If there is a high density of electric field lines at a point, ( if a higher number of field lines pass through that point) the electric field intensity of that point is high. If no lines of electric field lines pass through a point, the electric field intensity at that point is zero. (figure 02)
Properties of electric field lines
Electric field lines never intersect each other
Electric field-lines may start from positive charges and end at negative charges
Electric field-lines may start from positive charges and end at infinity
Electric field lines may start from infinity and end at negative charges
If there are no field lines at a point, the electric field intensity of that point is zero. That point is known as the 'Neutral point' (Figure 02).
There is always repulsion between field lines
Electric field-lines are perpendicular to the charged surface
Electric flux is the number of electric field lines across a unit area. The electric flux that passes perpendicular to a unit area, is the electric field intensity of that area.
φ = Electric flux
E = Electric field intensity
A = Surface area
If the field lines are not perpendicular to the surface, the electric flux can be calculated as follows.
Where θ is the angle between the surface and the field lines.
References and Attributes
The cover image was designed using an image by Geek3, licensed under CC BY-SA 3.0, via Wikimedia Commons