Electric Field Lines (NCERT) - Free MCQ Practice Test with solutions, NEET

Electric field lines are essential for understanding various aspects of electric fields. They illustrate:

• Field strength: The density of lines indicates how strong the electric field is; closer lines mean a stronger field.
• Direction: The arrows on the lines show the direction a positive charge would move within the field.
• Nature of charge: Lines emanate from positive charges and terminate at negative charges, visually representing their nature.

These characteristics together provide a comprehensive view of the electric field's behaviour and effects.

The field lines of a single positive charge are radially outward.

The field lines of single negative charge are radially inward.

For a uniformly charged hollow cylinder, the electric field lines are as shown in figure (b).

In the given figure, the electric lines of force emanate from A and C. Therefore, charges A and C must be positive.

From the given figure it is clear that, maximum number of electric lines of force are associated with charge C, so it must have the largest magnitude.

From the figure, it is clear that, there cannot be a neutral point between a positive and a negative charge. Neutral point can be only there between two like charges i.e„ A and C. As magnitude of charge A is smaller than the magnitude of charge C, therefore, neutral point would lie closer to the charge A.

Electric field strength is maximum where the electric field lines are closer.

Perpendicular to the Surface of Conductors: Electrostatic field lines are always perpendicular (at 90 degrees) to the surface of a conductor. This is because conductors contain free charges that can move freely within the material. When an electric field is applied, these free charges redistribute themselves on the surface of the conductor until the electric field inside the conductor is zero. This redistribution causes the electric field at the surface to be perpendicular to the surface.

In a charge-free region, electric field lines can be taken to be continuous curves without any breaks.