91Ó°ÊÓ

\(H\) is defined by the formula \(H = B/\mu - M\), where \(B\) is the magnetic flux density, which measures the real magnetic field present in a material as a concentration of magnetic field lines, or flux, per unit cross-sectional area;\(\mu \) is the magnetic permeability; and \(M\) is the magnetization.

The magnetic flux is denoted by:

\(\Phi = BA\cos (\theta ),\)

Where \(B\) is the magnetic field, \(A\) is the area of the loop and \(\theta \) is the angle formed by the loop perpendicular to the field lines.

As a result, the field does not have to be zero in order for the flux to be zero. If the magnetic field is not perpendicular to the surface, either the loop has no surface (in a theoretical case, the loop does not exist, or it is a point), or the magnetic field makes a right angle with the perpendicular to the surface. This means that the surface on which the loop is located is in the same plane on which the field lines are located.