The intensity of a magnetic flux is expressed by the number of magnetic lines of force in a square centimeter or square inch.
One barn is equal to 10-24 square centimeter, which is approximately the cross-sectional area of a typical atomic nucleus.
This hole measures exactly one square centimeter in area, and is circular.
Over 300,000 can find room upon a square centimeter of surface.
The practical limit of the magnetization of soft iron (called saturation) is 18,000 lines to the square centimeter.
