Unit IIA Magnetism Reference: Ch 20-26 Essential Question: How is magnetism different from electricity? Magnetic Properties Permanent Magnets A magnet is a material that has the ability to attract and repel other magnetic materials Permanent magnet – Material that keeps its magnetic properties, even when it is not close to other magnets—always a magnet! Poles (north and south) Even if you chop them in half, they retain their magnetic properties Magnets exert magnetic forces on each other The forces between magnets depend on the alignment of the poles –Like poles repel –Opposite poles attract Magnetic Field Developed to describe how a magnet exerts magnetic force Every magnet creates an energy field in the space around it The field exerts forces on any other magnet that is within its range Permanent magnets & Electromagnets Creating electromagnets – Send an electrical current through a coil of wire wrapped around some iron – Current controls the strength of an electromagnet—more current, stronger magnet Uses:Magnetically levitated trains (monorails) and roller coasters Electric currents cause all magnetism Electrons move creating small loops of current Iron attracts magnets because its atoms are free to rotate and align their north & south poles Force & Induction Electromagnetic force – An electrical and magnetic force between electrical charges Electromagnetic induction – A current is created in a wire by a moving magnet – The reverse is also true – Because a moving magnet induces electrical current to flow Generators Electric Motor Uses a permanent and an electromagnet. The electromagnet rotates in the permanent magnet’s magnetic field Creates current. Generators-make AC current using a coil of wire rotating in a magnetic field. This produces a current. Wire rotated by outside forces.