Electric Current from Magnetism Electromagnetic Induction Electromagnetic Induction • An electric current can be produced in a circuit by a changing magnetic field • This is referred to as Faraday’s Law Electromagnetic Induction • As the loop moves in and out of a magnetic field, a current is produced (or induced) in the conductor • A current can also be produced by rotating the circuit or changing the magnetic field Electromagnetic Induction • A current is only produced when the conductor moves perpendicular to the magnetic field • This is the only way that the individual charges experience a force from the magnetic field and move Alternating Current • As the loop of wire spins within the magnetic field between the two magnets, current is produced when the wire moves perpendicular to the field – “Flat” in the figure Alternating Current • When the loop moves parallel to the field, no current is produced – When the loop is “straight up and down” Alternating Current • In order for the loop to complete a full rotation, it becomes “flat” again, but this time it is moving the other direction – Current is produced, but it moves in the opposite direction Alternating Current • A current that changes directions at regular intervals AC Generator • Mechanical Energy is used to turn the coil of wire in a magnetic field • As the coil (which actually consists of many coils) is turned, alternating current is produced Electromagnetic Energy • James Clerk Maxwell develops equations in mid-1860’s to describe the nature of electromagnetic waves Electromagnetic Energy • Because the movement of charge produces a magnetic field and a magnetic field can produce a current, these two acting together can carry energy without using matter Electromagnetic Energy • These electromagnetic waves carry visible light, radio signals, and x-rays with different amount of energy