For transport phenomena, flux is a vector quantity, describing the magnitude and direction of the flow of a substance or property. In electromagnetism, flux is a scalar quantity, defined as the surface integral of the component of a vector field perpendicular to the surface at each point.

Electric Flux as a Scalar Quantity

Electric flux is defined as the amount of electric field passing through a surface. It is represented by the symbol ΦE and is a scalar quantity. Let's understand why electric flux is a scalar quantity.

Magnitude and Direction

A vector quantity has both magnitude and direction. However, electric flux is defined as a scalar product of the electric field and the surface area vector. The surface area vector is always perpendicular to the surface, which means its direction is fixed. Therefore, the direction of electric flux is the same as the direction of the electric field. This means that electric flux does not have a direction of its own.

Addition and Subtraction

Another characteristic of a vector quantity is that it can be added or subtracted from another vector quantity. However, electric flux cannot be added or subtracted from another electric flux. This is because electric flux is not a vector quantity and does not have direction.

Unit

The unit of electric flux is the volt-meter (V.m) or the newton-meter squared per coulomb (N.m2/C). This unit is a scalar unit and does not have direction.

Conclusion

Therefore, electric flux is a scalar quantity because it does not have direction, cannot be added or subtracted from another electric flux, and has a scalar unit.