Uniform Electric Fields: Understanding Coulomb's Law and Field Intensity

In summary, Coulomb's Law states that the force between two charges is directly proportional to the product of the charges and inversely proportional to the square of the distance between them. The intensity of a uniform electric field does not get weaker in the middle because it is not a linear function over distance. For an infinite planar charge distribution, Gauss's law must be used to determine the expression for the electric field. Alternatively, the field can be calculated by treating the sheet as a collection of point charges and integrating over the entire sheet. In either case, the result is a uniform electric field on either side of the sheet, in opposite directions.
  • #1
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Coulomb's Law
F = kqq/r^2

Why does the intensity of a uniform electric field not get weaker in the middle? I would understand this if the intensity over distance was a linear function, but it isn't. The force near one of the plates would approach infinity, because r^2 is so small... but in the middle of the field even the forces of each side added up would not approach infinity, which means the field is not uniform. How are uniform electric fields possible?
 

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  • #2
This is a very confusing post.

The expression for the Coulomb's law that you wrote is for a point or spherical charge distribution. Yet, you are talking about "plates" here.

For an infinite planar charge distribution, use Gauss's law and figure out the expression for the E-field. It is NOT the same as what you have written.

Zz.
 
  • #3
Or, you can find the electric field produced by a uniform plane sheet of charge by treating it as a collection of point charges and integrating over the whole sheet. If the sheet is large enough to be effectively "infinite" in size, you get the result that the field is uniform on either side of the sheet, in opposite directions on the two sides. (Using Gauss's Law is much quicker, if you know it and understand it.)
 

1. What is a uniform electric field?

A uniform electric field is a type of electric field in which the magnitude and direction of the electric field are constant at all points in space. This means that the force experienced by a charged particle placed in a uniform electric field will be the same at all points within the field.

2. How is a uniform electric field created?

A uniform electric field can be created by placing two parallel charged plates with opposite charges close to each other. The electric field between the plates will be uniform, as the charges on the plates will exert equal and opposite forces on any charged particles placed in the field.

3. What is the direction of the electric field in a uniform electric field?

The direction of the electric field in a uniform electric field is always perpendicular to the charged plates. This means that the electric field lines will be straight and parallel to each other.

4. How is the strength of a uniform electric field measured?

The strength of a uniform electric field is measured in units of volts per meter (V/m). This represents the amount of force experienced by a unit of charge (1 volt) placed in the field.

5. What are some applications of uniform electric fields?

Uniform electric fields have various applications in science and technology. They are used in particle accelerators to accelerate charged particles, in cathode ray tubes to produce images on screens, and in capacitors to store electric charge. They also play a crucial role in understanding the behavior of electrically charged particles in space.

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