**What is Flux?**

Flux means an imaginary or visual line passes through physical substances. The word flux comes from the Latin word “Fluxus,” which means flow or flowing out and was first introduced by Sir Isaac Newton into differential calculus as “fluxion.”. In mathematics and physics flux is used as the basic and global word.

For transport phenomena such as heat transfer and fluid dynamics, flux is a vector quantity, describing the magnitude and direction of the flow of a substance or property. Here the flux is rate of rate of flow of a property per unit area. For example, the amount of water flowing per square area of a river

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

**Types of Flux**

Various types of flux..

- Heat Flux
- Lumens flux
- Magnetic flux
- Electric Flux
- Mass flux
- Energy flux
- Momentum flux
- Acoustic Flux

**Magnetic Flux**

Magnetic flux is the measure of magnetic field lines passes through a closed surface. The SI (International Standard) units of magnetic flux is Weber and the CGS (Centimeter-Mass-Second) unit is – Maxwell. The symbolic representation of magnetic flux Φ_{B}. It is measured by Magnetometer

**Electric Flux**

- Electric flux means the rate of flow of electric field through a given area. If the electric field is uniform, the electric flux passing through a surface of vector area S is

- Electric flux is proportional to the number of electric field lines going through a virtual surface.
- The SI unit of Electrical flux is volt meters (V m).
- Electric Flux is denoted by Φ
_{E} - It is a quantitative measure of electric field line forces.

**Luminous Flux**

Luminous flux is the measure of perceived light energy or the measure of the total power of electromagnetic radiation (including infrared, ultraviolet, and visible light); it is visible to the human eyes… The SI unit of luminous flux is Lumen (lm). It is measured by lux meter.

**Radiant Flux **

Radiant flux means the line of transmitted radiated energy (energy of electromagnetic and gravitational radiation) per unit of time and spectral flux or spectral power is the radiant flux per unit frequency or wavelength, depending on whether the spectrum is taken as a function of frequency. from any energy source. The SI unit of radiant flux is Watt, that is joule/second (J/s). It is measured by a radiometer.

Radiant Flux is denoted as Φ_{e}. (“_{e}” for energetic)

Spectral flux is denoted as Φ_{e,v }and the unit of spectral flux is W/Hz (Watts per Hertz)

**Heat Flux**

Heat flux means the heat energy transfer through an elementary surface per unit of time. The SI unit of heat flux W/m^{2} or Wm^{-2} (Watt per square meter) It is denoted as Φ_{q}. Heat flux is measured by heat flux sensor.

**Mass Flux**

It means the rate of mass flow per unit area. Its SI unit is kg/s-m^{2} or kg s^{-1} m^{-2}.. It is denoted as J or Q or q.

### Momentum Flux

Momentum flux, the rate of transfer of momentum across a unit area (N·s·m^{−2}·s^{−1}).

### Acoustic Flux

It means flow of sound energy through unit area per second. Its SI unit is Watt.

### Volumetric flux:

The rate of volume flow across a unit area. The unit of Volumetric flux is m3·m−2·s−1

### Diffusion flux:

The rate of movement of molecules across a unit area. The SI unit of diffusion flux is mol·m−2·s−1

### Particle flux:

The rate of transfer of particles through a unit area (number of particles), SI unit of Particle flux is m−2·s−1