Explain the electric field lines and the magnitude of the electric field.

(N/A) Electric field lines are a pictorial representation of the electric field produced by a charge or a system of charges.
To visualize this,draw vectors pointing along the direction of the electric field with their lengths proportional to the strength of the field at each point.
Since the magnitude of the electric field at a point decreases inversely as the square of the distance of that point from the charge,the vector gets shorter as one moves away from the charge,always pointing radially outward for a positive charge and radially inward for a negative charge,given by $E = \frac{kQ}{r^{2}}$.
In the figure,each arrow indicates the electric field,i.e.,the force acting on a unit positive charge placed at the tail of that arrow. Connecting the arrows pointing in one direction results in a field line.
The magnitude of the field is represented by the density of the field lines.
$\overrightarrow{E}$ is strong near the charge,so the density of field lines is higher near the charge and the lines are closer together. Away from the charge,the field becomes weaker and the density of field lines decreases,resulting in well-separated lines.