Electric field lines – 12
Today we are going to discuss about electric field lines, properties of electric field lines, electric dipole and dipole movement.
● Electric field lines and Field lines are same things.
Define electric field lines
Electric field lines are imaginary lines in a region of space along which a free +ve charge would move if allowed to do so.
• Electric field lines are not real.
Properties of electric field lines
Here are some properties of electric field lines.
● Electric field lines originated from positive charge and terminate at negative charge.
Means, they rise from +ve charge and finish at
● They doesn’t form closed loop, like magnetic field.
Means, electric field lines doesn’t come back to the initial point.
● The number of electric field lines are subjective but density of field lines are objective.
● The number of field lines from / to a point charge is directly proportional to the magnitude of the charge.
● Electric field lines are symmetric about the line joining two charges.
● Maximum angle between field lines means there are less field lines present.
Eg. A charge only releases 4 field lines, it means angle between them is 90 degree.
A charge releases 10 field lines, it means angle between them is 36 degree.
● The density / relative closeness of field lines gives magnitude of field.
Where field lines are close there magnitude of field lines is maximum.
● Electric field lines are perpendicular to the surface of charge.
● The tangent drawn on field lines gives the direction of electric field at that point.
● Two electric field lines can never intersect each other.
● Positive charge repel electric field lines and negative charge attracts electric field lines.
● Parallel, straight and equispaced field lines represent uniform electric field.
● Under electrostatic condition electric field inside a conductor is absent.
● Field lines are perpendicular to the surface of a conductor.
What is electric dipole ?
Electric dipole is an arrangement of two equal and opposite charges which are separated by a small distance.
Importance in 12 physics
Electric field, electric field lines and properties of electric field lines plays an important role in 12 class physics CBSE.
These concepts helps us to understand electric charges properly and easily, properties of electric field lines helps us to solve numericals and HOTS questions easily.
What is dipole movement (P)
Dipole movement is the product of charge and separation between them.
Dipole movement is a vector quantity.
Direction of dipole movement is -ve to +ve.
Here are some frequently asked questions.
1. What is mean by electric field lines ?
Electric field lines are the imaginary lines.
2. What are electric field lines class 12 ?
Electric field lines are defined as the the imaginary lines in a region of space.
3. What is electric field lines and its
Already answered above.
4. Where do electric field lines originated ?
Electric field lines are originated in positive charge.
5. Where do electric field lines terminated ?
They terminated at -ve charge.
6. Where is the electric field strongest ?
The region where field lines are close to each other, there the electric field is strongest. And the region where electric field lines are at a distance from each other, there electric field is weak.
7. What are the three rules of drawing electric field lines ?
• You should always draw electric field lines from high to low potential.
• Never intersect any field lines.
• Field lines from a positive charge is always radially outwards, but from negative charge its radially inwards.
8. Can electric field lines cross ?
The answer is no, field lines can never intersect.
9. What is uniform electric field ?
Field lines which are parallel, straight and equispaced are termed as uniform electric field.
10. Which charge repel field lines ?
Positive charge repel field lines whereas negative charge attracts electric field lines.