# Magnetic Flux - Formula, SI Unit & CGS Unit

Magnetic Flux

A sub-discipline of physics in the field of electromagnetism is the magnetic flux through a surface, which refers to the surface integral of the magnetic field's (B) normal component passing through that surface. To be specific, magnetic flux is defined as the number of magnetic field lines passing through a given closed surface. In this particular scenario, the area under consideration can be in any orientation corresponding to the direction of the magnetic field and of any size.

Symbol and Formula of Magnetic Flux

Magnetic flux is denoted by the Greek letter Phi and has the symbol Φ or ΦB

To calculate the magnetic flux, we can use the formula given below:

ΦB = B.A = B A cosΦ

Where,

ΦB = Magnetic Flux

B = Magnetic Field

A = Area

Φ = Angle at which the magnetic field lines pass through the given surface area

Fluxmeter is used to measure magnetic flux.

SI Unit of Magnetic Flux

Weber (Wb) is the SI unit of magnetic flux, which is named after Wilhelm Eduard Weber, a German physicist. A flux density of one Weber per square meter or Wb/m2 is one Tesla, denoted by T (explained in the next section). Quite often, Weber is expressed in a multitude of other units, as shown below:

Wb = kg m2/s2 A = V.s = H.A = T.m2 = J/A = 108Mx

Where, Wb = Weber, T = Tesla, V = volt, m = meter, J = joule, s = second, H = Henry, A = ampere, and Mx = Maxwell.

CGS Unit of Magnetic Flux

The CGS unit of magnetic flux is Maxwell (Mx) or Abweber (abWb).

Fundamental Unit of Magnetic Flux

The fundamental unit of magnetic flux is Volt-seconds.

Understanding the Term Magnetic Flux Density

The force acting per unit length on a wire placed perpendicular (at right angles) to the magnetic field per unit current is the magnetic flux density (B).

• Tesla (T) or Kg s-2 A-1 is the SI unit of magnetic flux density (B).

• The magnetic flux density, denoted by the symbol B, is a vector quantity

• The CGS unit of magnetic flux density is Gauss, which is abbreviated as G or Gs

The formula for calculating the magnetic flux density is as follows:

B = F/I L

Where,

F = total force acting on the wire

I = current flowing through the wire

L = length of the wire

## Submultiples of Weber(Wb)

 Value SI Symbol Name 10-1 Wb dWb deciweber 10-2 Wb cWb centiweber 10-3 Wb mWb milliweber 10-6 Wb µWb microweber 10-9 Wb nWb nanoweber 10-12 Wb pWb picoweber 10-15 Wb fWb femtoweber 10-18 Wb aWb attoweber 10-21 Wb zWb zeptoweber 10-24 Wb yWb yoctoweber

## Multiples of Weber

 Value SI Symbol Name 101 Wb daWb decaweber 102 Wb hWb hectoweber 103 Wb kWb kiloweber 106 Wb MWb megaweber 109 Wb GWb gigaweber 1012 Wb TWb teraweber 1015 Wb PWb petaweber 1018 Wb EWb exaweber 1021 Wb ZWb zettaweber 1024 Wb YWb yottaweber