# Electricity Formula: Difference between E=σ/2ε0 and E=σ/ε0

• Astronomy
In summary, the first formula is used for a thin sheet and the second formula is used for the surface of a metal.
Astronomy
Hi
I want to know what is the diffrences between E=σ/2ε0 & E=σ/ε0
of course I know we use the first for a very huge page but what about the second formula?
I saw in some solving of question when we have 2 pages infront of each others we use both of them...
I want to understand the deep meaning and usage...
pls tell me simply beacuse my profession english is not good!
thank u

The first formula is used for a thin sheet where the field lines split half in each direction. The second formula is used for the surface of a metal where all the field lines are in one side of the surface (outward), and there is no field in the other side (inward).

## 1. What is the difference between E=σ/2ε0 and E=σ/ε0?

The main difference between these two equations is the value of the constant in the denominator. In the first equation, the constant is divided by 2, while in the second equation, the constant is not divided. This difference results in a different value for the electric field strength.

## 2. Which equation is more accurate?

Both equations are accurate and can be used to calculate the electric field strength. The choice of which equation to use depends on the specific situation and the level of accuracy needed. In general, the first equation (E=σ/2ε0) is more commonly used, but the second equation (E=σ/ε0) may be more appropriate in certain situations.

## 3. What do the variables in the equations represent?

The variable E represents the electric field strength, measured in volts per meter. The variable σ (sigma) represents the surface charge density, measured in coulombs per square meter. The variable ε0 (epsilon naught) represents the permittivity of free space, which is a constant value.

## 4. How do these equations relate to Coulomb's law?

These equations are derived from Coulomb's law, which states that the electric field strength is directly proportional to the surface charge density and inversely proportional to the permittivity of free space. The constant in the equations is used to account for this relationship.

## 5. When should I use these equations?

These equations are commonly used in the field of electrostatics, which deals with stationary electric charges. They can be used to calculate the electric field strength at a specific point in space due to a given surface charge density. These equations are also used in various fields of engineering, such as electrical engineering and materials science.

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