Electric Field Between Two Plates: Magnitude, Direction, Examples & More

Electric Field Between Two Plates: By remembering the basic concept of Electric Field from Coulomb’s Law,  that represents forces acting at a distance between two charges. We can reform the question by breaking it into two distinct steps, using the concept of an electric field. First, Think of one charge as generating an electric field everywhere in space. Second, The force on another charge brought into the electric field of the first is caused by the electric field at the location of the introduced charge.

If all charges are stationary, you get definitely the same answers with the electric field as you do use Coulomb’s Law. So, is this going to be just training in clever notation? No. The electric field concept appears on its own when charges are granted to move relative to each other.

Experiments show that only by considering the electric field as a property of space that transmits at a finite speed (the speed of light), can we account for the noticed forces on charges in relative motion. The electric field concept is also compulsory for understanding a self-propagating electromagnetic wave such as light.

The electric field concept gives us a way to represent how starlight travels through vast distances of empty space to reach our eyes. If the idea of force acting at a distance in Coulomb’s Law seems troublesome, perhaps the idea of force caused by an electric field moderate your annoyance somewhat. On the other hand, you might also question if an electric field is any more real.

Electric Field Between Two Plates
Electric Field Between Two Plates

The phenomenon of an electric field is a topic for theorists. In any case, real or not, the notion of an electric field turns out to be useful for foreseeing what happens to charge. We introduce an electric field initially between parallel charged plates to ease into the concept and get practice with the method of analysis.

In this article, learn how to calculate the electric field between two charged parallel plates and also see the effect of this field on other charges.

Electric Field Between Two Charged Parallel Plates

Suppose that you have a very small metallic ball that is positively charged. You let it go, and it starts moving to the right, going faster and faster the farther away from you it gets. You can see that nothing touched it, but you can also see that something must have exerted a force on this charged object to make it speed up like that. What was it?

All charges generate an unseen electric field around them. This field can then exert a force on any other charges that are placed near to them. The positively charged ball that you released feels a force due to the existence of an electric field that must have been generated by some other charges that were nearby.

Electric fields exert forces on both positive and negative charges, but the direction of the force depends on both the direction of the field and the type of charge (positive or negative) that the object has. Positively charged objects will always feel a force in the same direction of the electric field, while negatively charged objects will always feel a force in a direction opposite to the electric field.

The magnitude of Electric Field

One way to generate a uniform electric field is to place two plates close to each other, then give one of them a positive charge and the other an equal negative charge. This will create an electric field between the plates that is directed away from the positively charged plate and towards the negatively charged plate.

Electric Field Direction Between Two Charged Plates
Electric Field Direction Between Two Charged Plates

If the size of the two charged plates is a lot bigger than the distance between the plates, then the electric field between the plates will be constant. It’s easier to find out the magnitude of this electric field. You only need to know the total amount of charge on each plate (Q) and the area of each plate (A).

The distance between the plates does not actually matter, as long as it is much smaller than the diameter of the plates.

Let’s look at an example of how to calculate the electric field between two charged parallel plates:

Example: If each plate is circular with a radius of 10 cm, and each has a total charge of 0.05 C, what is the magnitude of the electric field between these plates?

First, find the area of the plates.

Example Of Electric Field Magnitude
Example Of Electric Field Magnitude

Then use this area to calculate the magnitude of the electric field between the plates.

Calculation Of Electric Field Magnitude
Calculation Of Electric Field Magnitude

The motion of a Charged Particle

Now let’s see what would appear if you sent a moving charge into space between two charged plates.

The electric field between these plates will exert a force on this charge, so the first thing you need to do is determine which direction the force will be exerted on this charge.

According to our assumption, the positively charged particle feels a force in the direction of the electric field. The acceleration of a particle between the plates is proportional to the magnitude of the electric field. A positively charged particle moves toward the negative plate, a negatively charged toward the positive.

FAQ

Is The Electric Field Between Two Plates Uniform?
Since The Field Lines Are Parallel And The Electric Field Is Uniform Between Two Parallel Plates, A Test Charge Would Experience The Same Force Of Attraction Or Repulsion No Matter Where It Is Located In The Field. Field Lines Always Point From Regions Of High Potential To Regions Of Low Potential.
What Is The Direction Of The Electric Field Between The Plates?
In What Direction Does The Electric Field Between The Plates Point? The Electric Field Points From The Positive To The Negative Plate- Left To Right.
What Is The Electric Field Between Two Oppositely Charged Parallel Plates?
The Electric Field E Between Two Oppositely Charged Parallel Conducting Plates Is Uniform I.E. It Has The Same Magnitude And Direction Everywhere Between The Plates.
Can Electric Field Be Negative?
Electric Field Is Not Negative. It Is A Vector And Thus Has Negative And Positive Directions. An Electron Being Negatively Charged Experiences A Force Against The Direction Of The Field. For A Positive Charge, The Force Is Along The Field.
What Is The Formula Of Electric Field?
The Magnitude Of The Electric Field (E) Produced By A Point Charge With A Charge Of Magnitude Q, At A Point A Distance R Away From The Point Charge, Is Given By The Equation E = Kq/R2, Where K Is A Constant With A Value Of 8.99 X 109 N M2/C2.
What Is The Relationship Between Voltage And Electric Field?
Voltage Related To Electric Field. [Assuming Constant Field And Motion Parallel To The Field]. In Other Words, The Difference In Voltage Between Two Points Equals The Electric Field Strength Multiplied By The Distance Between Them.
Where Is The Electric Field Strongest?
The Relative Magnitude Of The Electric Field Is Proportional To The Density Of The Field Lines. Where The Field Lines Are Close Together The Field Is Strongest; Where The Field Lines Are Far Apart The Field Is Weakest. If The Lines Are Uniformly-spaced And Parallel, The Field Is Uniform.
Is The Electric Field Always Positive?
An Electric Field Is Neither Positive Or Negative. It Is Defined As Being The Force Acting Per Unit Positive Charge. (This Means It Is A Vector Like Force Is). If You Move A Positive Charge In The Direction Of An Electric Field, Work Is Done By The Charge.
Why Does Electric Field Go From Positive To Negative?
The Direction Of Electric Fields Is Always Defined As The Direction A Positive Test Charge Would Move If It Was Dropped In The Field. A Negative Charge Has An Inward Electric Field Because It Attracts Positive Charges. The Positive Charge Has An Outward Electric Field, Pushing Away Like Charges.
Does Electric Field Increase With Voltage?
A Capacitor Has An Even Electric Field Between The Plates Of Strength E (Units: Force Per Coulomb). So The Voltage Is Going To Be E×distance Between The Plates. Therefore Increasing The Distance Increases Voltage. As Charge Remains Constant, Per Charge Energy Increases As Well (That Is Potential Difference).