Electric flux density and confusion about units

In summary, electric flux density is defined as the electric flux per unit area, with a SI unit of N/C. However, according to the formula D=epsilon*E, the SI unit is C/m^2. This may cause confusion, but it can be resolved by considering the corresponding flux of the displacement field, which is related to the flux of the electric field through the equation Phi_D=epsilon*Phi_E. This clarifies the discrepancy in units.
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sunil36
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My general understanding of electric flux density is 'electric flux per unit area'. This gives the SI unit N/C. But According the formula of electric flux density, D=eplison*E, the SI unit is C/m^2. How come the dimension in both cases not matching if both are true?
 
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I think there's some terminological confusion. If you're planning on calling ##\vec D## the flux density then the corresponding flux is the flux of the displacement field, ##\Phi_D=\int \vec D\cdot d\vec S##. That's related to the flux we discussed in your other thread, ##\Phi_E=\int \vec E\cdot d\vec S##, as ##\Phi_D=\varepsilon \Phi_E##. I think that should sort out the units.
 
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FAQ: Electric flux density and confusion about units

1. What is electric flux density?

Electric flux density, also known as electric displacement, is a measure of the electric field that passes through a given area. It is represented by the symbol D and is measured in units of coulombs per square meter (C/m^2).

2. How is electric flux density different from electric field?

Electric flux density is a measure of the electric field that passes through a given area, while electric field is a measure of the force exerted on a charged particle in an electric field. Electric flux density takes into account the material properties of the medium, while electric field does not.

3. Why is there confusion about units for electric flux density?

There is often confusion about units for electric flux density because it is sometimes represented by the same symbol (E) as electric field. Additionally, the units for electric flux density (C/m^2) are the same as the units for electric displacement (D), which can lead to further confusion.

4. How can I convert between units for electric flux density?

To convert between units for electric flux density, you can use the formula D = εE, where ε is the permittivity of the medium. The permittivity has units of farads per meter (F/m), so by multiplying by this factor, you can convert between C/m^2 and V/m.

5. How is electric flux density used in practical applications?

Electric flux density is used in a variety of practical applications, such as in the design of capacitors and in the study of dielectric materials. It is also used in the calculation of electric displacement current, which is important in the study of electromagnetic waves and circuits.

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