# Regarding magnets, what is the ease with which a substance passes magnetic lines?

Permeability

Explanation

Magnets have several properties that describe them. Permeability is the ease with which a substance passes magnetic lines and reluctance, its opposite, is the opposition that a substance offers to magnetic lines. Retentivity measures the degree to which a substance remains magnetized after the magnetizing force is removed. Magnetic flux is the quantity of magnetism expressed by total number of magnetic lines of force and flux density measures the strength of magnetic flux across a unit of area (typically $$1 \mathrm{~cm}^{2}$$ ).