magnetism

• the region around a magnet, where where a force acts on another magnet is called the magnetic field.
• permanent magnets induce thier own magnetic fields
• induced magnets become magnetized when placed in a magnetic field, when taken out, they lose their magnetism.
• the arrows on field lines always from the north pole to the south
• the density of field lines is called flux density and indicates the strength of the field at that piont.
• whenever a current flows in a conducting wire, a magnetic field is produced around the wire
• a solenoid is formed when a wire is looped around a cylindrical coil, shaping the wire into a solenoid increases the strength of the magnetic field, creating a strong uniform field
• to increase field strength further, an iron core can be added, creationg an electromagnet.
• a solenoid increases the magnetic field strength because it- concentrates a longer piece of wire into a smaller area, the looped shape means the magnetic field lines around the wire are all in the same direction.