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# Electric field definition

Michael Faraday proposed that electric fields are present around objects with charge, which allows the electric force to act on charged objects which are not in contact. An electric field causes an electric force on other charges that enter the field. The electric field is defined as the amount of electric force per charge at a point in space. Created by David SantoPietro.

## Want to join the conversation?

• why cant a charge experience a force on itself by its own electric field(its silly but it always bugs me)
• Maybe it can, but since it's pushing itself with the same force from all directions, the result is the same as if it wasn't doing anything.

It would be weird if it was pushing more in one direction than others, right? Where would that asymmetry come from?
• so what is an electric field made of exactly?
• The electric field is merely a concept to help us explain forces on charges. In other words, the electric field isn't made of matter but tells us how much force a given charge will feel in a given position. That's the only point of the electric field.
Like, you could also say "What is force made of?" Well, it's just an abstract concept to explain why masses can change velocity.
• 'WHY' does an electric field of charge A supposedly cause a force on another charge B, supposedly? Why?
• The short (and somewhat unsatisfactory) answer is no one knows. That's just the way electric charges behave and we have created mathematical models to predict that behavior. Does the electric field actually exist? Maybe not, but it is the mathematical tool we use to correctly explain the force between charges.

Watch this video where Feynman explains the difficulty with why questions:
• is the direction of electric field and electric force same?
• Not always. The vector equation for Electrostatic force can be written as:
`F` = q • `E`
where the highlighted characters `F` and `E` denote that they are vectors.
If the test charge q is positive then `F` and `E` will have the same sign. But if q is negative, `F` will be in a direction opposite to that of `E`.

Hope this helps.
• So the electric force and electric field are almost the same.
• no. not quite.

electric force is the pull or push that an electric charge will experience. units = newtons for force

Electric field is the region in which that force is felt.

The electric field strength = force per unit charge units = newtons per coulomb

ok??
• so will a charged particle in an electric field always move along electric field lines?
• not necessarily. The force will always be along the field lines but if the charge already has motion perpendicular to the field, then its dircetion / speed will change.

ok?
• what bout the distance at which the charge is placed
• If electric field causes two protons to repel then what causes to masses to attract by gravitation?
• why dont like charges attract each other
• The easiest way of looking at why opposite charges attract each other and like charges repel is to look at fields and how charges affect the field and react to the field. There is an electromagnetic field throughout all of space and this field has an amount of energy in it that can varry from location to location.

First let’s look how a charge will affect the electromagnetic field. With no charges the field will have zero energy, a positive charge will increase the amount of energy in the field and a negative charge decrease the energy, the energy in the field can be negative. The effect of a charged particle on the field near the particle will decrease with the square of the distance from the charge. When there are multiple charged particles the total energy at a point will just be the sum of the energies contributed by the particles.

Next let’s look at how a particle will react to an electromagnetic field. If the particle is neutral and has no charge it will not be affected by the field. A positively charged particle will experience a force away from higher energy locations to lower energy locations in the field. A negatively charged particle will experience a force away from lower energy locations towards higher energy locations in the field.

Putting these two things together when you have a charged particle it will experience a force away from a like charge and towards a opposite charge. Looking at this in more detail lets assume we have a positive charge. As it gets near another positive charge it will encounter an increasing amount of energy in the field in the direction of the other positive charge and this causes a force away from the other charge. If our positive charge gets close to a negative charge it encounters a decreasing amount of energy in the direction of the other charged particle causing a force towards the other charge. If you go through this logic with a negative charge the same type if things occurs where the negative charge is experiences a force towards a positive charge and away from a negative charge.