FORT MYERS, Fla. A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other materials such as iron, and attracts or repels other magnets.  In the last week, magnets were involved in two studies related to our children.  Here to discuss these is Dr. Annette St. Pierre-MacKoul.