Weber, VAY buhr or WEE buhr, is a unit used to measure a magnetic field. A magnetic field is the influence that a magnet or electric current creates in the region around it. You can picture a magnetic field by placing a sheet of paper on a bar magnet and sprinkling iron filings on the paper. The filings will line up to make loops, called magnetic field lines, that connect the poles of the magnet. The magnetic field is strong where the field lines are close together, as they are near the poles.