# Magnetic  Flux

The magnetic flux is proportional to the number of

field lines that pass through the surface.

Φ = Bn A

• Φ   magnetic flux in Wb (Weber).  Also :  T m2 of Vs
• Bn   the component of B perpendicular to the  surface in T(esla)
• A     area of the surface  in m2

Example

See the drawing above.

B = 1.5 x 10-3 T

A = 500 cm2

α = 40 o

Resolve B in both components  and calculate Bn

sin α = Bn/B

Bn = B sin 40 o = (1.5 x 10-3)( 0.643) = 9.642 x 10-4  T

Φ = Bn A

Φ = (9.642 x 10-4 )( 500 x 10-4)= 4.82 x 10-5 Wb