Faraday’s Law of Induction and The Correlation between Biot-Savart Concept

        Faraday’s Law and Biot-Savart equation become 2 basic concepts respectively in designing electric generator or magnetic generator that have been used in many application field, for example, producing electric power by power generator to supply town’s electricity or especially producing high frequency AC magnetic field to cause heat loss in super paramagnetic magnetic nanoparticle for hyperthermia treatment. We’ve already learned about the Biot-Savart’s equation that simply said if the magnetic field can be produced along wire carrying an electric current. Now, Faraday’s concept tells reversely.

          Any change of magnetic environment in a coil of a wire will cause a voltage (Electromotive Force: EMF) to be induced in the coil. No matter the change is produced, the voltage will be generated. The change could be produced by changing  the magnetic field strength, moving magnet toward or away from  the coil, moving the coil into or out the magnetic field, rotating the coil relative to the magnet, etc.

         Faraday’s law is fundamental relationship which comes from Maxwell’s equation. It serves as a succinct summary of the ways a voltage (or EMF) may be generated by changing magnetic environment. The induced EMF in a coil is equal to the negative of the rate of change in magnetic flux times the number of turns in the coil. It involves the interaction of charge with magnetic field.

          Understanding Faraday's law requires understanding the concept of magnetic flux. The magnetic flux is a way of measuring the total amount of magnetic field over a surface or a surface area. An example might be the area of the coil of wire in the above experiments. If the magnetic field direction is perpendicular to the surface, then the magnetic flux is the magnetic field multiplied by the surface area. If the magnetic field is not perpendicular, then this product must also be multiplied by the cosine of the angle between the magnetic field direction and the outward pointing line perpendicular to the surface. This line perpendicular to the surface is called the normal.

じゃあ、Faraday's Law のことが分かてしまいましたか。