Magnetism From Electricity

Magnetic Field of a Current Carrying Wire 1820 – Hans Christian Øersted – demonstrated that a current carrying wire would deflect a compass needle Proved the relationship between electricity and magnetism A long, straight current carrying wire has a cylindrical magnetic field Compass needles will point in a circle surrounding the wire in the direction of the induced magnetic field Use the right hand rule to determine the direction of the magnetic field If you point your right thumb in the direction of current Your fingers coil in the direction of the magnetic field The magnitude of the magnetic field, B, is the same for every point on a circular path for a given distance from the wire, lying in a plane perpendicular to the wire Directly proportional to the current in the wire and inversely proportional to the distance from the wire

Magnetic Field of a Current Carrying Wire

Magnetic Field of a Current Carrying Wire

Magnetic Field of a Current Carrying Wire

Magnetic Field of a Current Loop The right hand rule can also be used to determine the direction of the magnetic field in a current carrying loop As long as the thumb is pointed in the direction of current, the fingers will curl in the direction of the magnetic field Solenoid – a long, helically wound coil of insulated wire Acts as a magnet when it carries a current The more loops in the solenoid and the stronger the current, the greater the magnetic field Inserting an iron rod into the center of the coil increases the magnetic field and produces an electromagnet Uniform magnetic field inside the solenoid, and a variable magnetic field outside the solenoid Used in many household appliances, automobiles, medical equipment

Magnetic Field of a Current Loop Magnetic Field in a Current Carrying Loop

Magnetic Field of a Current Loop