Electric Field Lines

Electric field lines are a representation used to visualize the electric field surrounding charged objects. They provide a way to understand the direction and strength of the electric field at different points in space. It helps analyze electric fields in various situations, such as around point charges, between parallel plates, or within complex arrangements of charges.

In this article, we will learn in detail about electric field lines, their properties, and the rules to draw electric field lines for different charges.

What is Electric Field Line?

The concept of an electric field line is used to define an electric field near charged particles. They were first used by Michael Faraday to define an electric field due to an electron and a proton.

Electric field lines are imaginary lines that are used to visualize electric field around a charge in real life. They are also called electric lines of force. The tangent drawn at any point on electric field lines shows the direction of electric field at that particular point.

They are regular lines without any break and are curved in nature. They are curved in nature and not linearly straight. In case of the positive charge the direction of electric field lines is radially outwards and in case of negative charge the direction of electric field line is radially inwards. Also, the density of the electric field lines shows the strength of the electric field i.e. the more electric field lines in an area the more the strength of the electric field there.

Properties of Electric Field Lines

The electric field lines have the following properties:

• Electric field lines never intersect each other.
• Electric field lines are always perpendicular to the surface of the charge.
• For a single charge, the field lines go from the surface of the charge to up to infinity.
• The magnitude of the electric field and the number of field lines, both are proportional to each other.
• In a uniform electric field, field lines are evenly spaced and parallel to each other.
• In a non-uniform electric field, the field lines are closer together where the field is stronger and farther apart where it is weaker.
• Electric field lines originate from positive charges and terminate on negative charges.

Rules for Drawing Electric Field Lines

The rules used for drawing electric field lines are discussed below:

• For positive charge, electric field lines always start at their surface and go up to infinity, for negative charge it starts from infinity and ends at its surface.
• The more field lines in an area the more the strength of the electric field.
• Electric field lines never intersect each other.
• Electric field and electric field lines are always tangent at the point where they pass through.

Electric Field Lines for Different Charges

Using the above rules we can draw electric field lines for different configuration of electric charges

Electric Field Lines for Individual Charges

In case of individual positive charge, the direction of electric field line is radially outwards and in case of individual negative charge the direction of the electric field line is radially inwards.

Electric Field Lines for Two Equal and Unlike Charge

For two equal and unlike charge the electric field will originate from positive charge and enter into negative charge forming a close loop

Electric Field Lines for Two Equal and Like Charge

In case of two equal and like charge both will exert repulsive force on each other and the arrangement of electric field lines will be either side of each charge.

Solved Examples on Electric Field Lines

Example 1: At any time, a force of 10 N is operating on the charge of 18 μC. Determine the intensity of the electric field at that location.

Solution:

Given: 
F = 10 N, q = 18 μC

E = F/q
E = 10 / 18 × 10^-6
E = 5.5 × 10⁵ N/C

Example 2: Calculate the strength of the electric field at a distance of 12 cm with a voltage of 68 V.

Solution:

Given:
V = 68 V, r = 12 cm

E = V/r

E = 68/12
E = 5.66 V/cm

Example 3: A force of 12 N is acting on the charge of 27 μC. Find Electric Field.

Solution:

Given: 
F = 12 N, q = 27 μC

E = F/q

E = 12 / 27 × 10^-6
E = 4.44 × 10⁵ N/C

Example 4: The electric field is 6.4 N/C at a distance of 6 cm then find the voltage.

Solution:

Given: 
E = 6.4 N/C, r = 6 cm

V = E × r

V = 6.4 × 6
V = 38.4 V

FAQs on Electric Field Lines

What electric field line are also called?

Electric field lines are also called as electric lines of force

What is electric field?

Electric field is the region around a charge in which it exerts a force on other charge

What is the SI unit of the Electric Field?

N/C (Newton/Coulomb) is the SI unit for an electric field.

State Coulomb’s law in Electrostatics.

Coulomb’s Law states that, “Magnitude of the electrostatic force of attraction or repulsion between any two point charges is directly proportional to the product of their magnitudes, and is inversely proportional to the square of the distance between them.”

What is an electric charge?

Electric Charge is the property of any particle by the virtue of which any particle experience forces in an electric and magnetic field.

What is the relation between electric field strength and density of lines?

Electric field strength is directly proportional to the density of electric field lines.

How is electric field strength related to distance?

Electric field lines follows inverse square rule with distance i.e. E ⋉ 1/r²