When Is Electric Field Zero? 5 Facts You Should Know

Electric field is a force of a charge that creates a region around its vicinity where its effect remains. Let us focus on that specific case of the electric field being zero.

Electric field is zero when two charges connected through a line have equal electric field intensity. If a particle is moving from one point to another and both the charges that are present at these points possess the same electric field intensity then the net change of electric field of that particle is zero.

To calculate the particular point of a line where the electric field is zero,electric field intensities of the two charges are to be made equal to each other.

When is the electric field always zero?

The value of electric fields depends on the values of charges and distance between them. Let us have a look at the conditions when the electric field is zero.

The electric field is always zero when the movement or flow of charges in a conductor is zero. As flow of charges represents the flow of current,the absent flow of charges depicts the value of current to be zero. This null value of current makes the electric field zero.

The electric field of an insulator is always zero. This is because the charges are bound and no flow of charges occurs in an insulator. This in turn makes the electric field zero.

Image Credit : Electric dipole field lines by Sharayanan (CC BY SA-4.0)

How is the electric field zero?

Electric field of a charge is a vector quantity directed away from a positive charge and towards a negative charge. Let us focus on the process of electric fields being zero.

The electric field sometimes becomes zero due to two charges along the same line are in opposite directions and of equal magnitudes then they tend to cancel each other.

In the case of two unlike charges the electric field can never be zero at any point between them as both the field vectors will be directed towards the negative charge.

What happens when the electric field is zero?

There are a number of conclusions that can be drawn when the electric field is zero. Let us discuss the effects of zero electric field.

When the electric field of two charges along a same line is zero, it depicts that the charges are equal in magnitude and they are like charges. Besides, charges that are not necessarily on the same plane make the electric field zero at a point due to the fact that the sum or net field at that point is zero.

The zero electric field at a point also concludes that there may be absence of charges around it.

Why is the electric field zero inside a sphere?

The value of the electric field inside a sphere is decided by the value of electric flux inside it. Let us know the reason for the electric field being zero inside a sphere.

The electric field is zero inside a sphere because not even a quantum of charges is present inside it. The electric field lines or the electric flux through a surface are generated from the charges. Absence of charges inside the sphere makes it unable to produce electric field lines inside it.

As the electric field lines pass uniformly in all directions from the charges kept above the surface of the sphere,they must cross the inner space of the spheres too but as the electric field field is a vector,the net electric field or the sum of electric fields remains zero.

Problem

Two point charges +9 Coulomb and +1 Coulomb are placed at a distance of 10 cm from each other along a straight line in the air medium. Find out the position from the smaller charge where the electric field is zero.

Answer :

The required formula for calculating electric field of a point charge in air medium is given by,E= q/4πε0.r² where ε0 = permittivity in air

Here, q1= 9 C and q2= 1 C

Let us assume that the point where the electric field is zero is at a distance x cm from the smaller charge.

Therefore the distance at which the electric field is zero from the larger charge is=(10-x) cm

Therefore  E1=  q1/4πε0.(10-x)² =  9/4πε0.(10-x)² and E2= q2/4πε0.x²= 1/4πε0.x²

As E1=E2

⇒9/4πε0.(10-x)² = 1/4πε0.x²

⇒9/(10-x)² = 1/x²

⇒9x² = (10-x)²

⇒(3x)² = (10-x)²

⇒3x = 10 -x

⇒4x = 10

⇒x = 10/4

⇒x= 2.5 cm

At a distance of 2.5 cm from the smaller charge the elecric field is zero.

Conclusion

All the facts that are when and why the electric field is zero between two point charges,why the electric field is zero inside a charged sphere and problems of electric field being zero related to the concept when the electric field is zero are covered within this article in a brief way.

Scroll to Top