There is ONLY one method of electrical Generation taught in textbook: By variation of Magnetic field, we either vary the strength or density of the Magnetic flux. There are two ways to create the variation of Magnetic field, one is through varying the distance of a fixed source of Magnetic field emanating object, another is through varying the voltage and current of electrical current enter and exit an electromagnetic coil. Thus, in this sense, all electrical Generation is in its heart a disguised process of mutual induction. Thus understand the details of mutual induction is the key to understand the process of electrical generation. I am going give you my ’spring’ analogy of electrical generation here.
We could thought of Permanent Magnet as a spring. As generating coil approach it in the Generator, the spring is kicking the electrons in the generating coil to action. However, it doesn’t just kick once, it is the changing of the electromagnetic stress on the generating coil created electromotive force(emf). Due to the design of generating coil, those emf is able to formed electrical current to flow in the generating coil in such a way that formed magnetic poles in the generating coil. Using the spring analogy, the spring is hitting the space inside the generating coil, and to maintain its neutrality/balance of each point mass in the generating coil, the coil kicks back. However, the different between generating coils and magnets is that generating coil is soft in a sense that it doesn’t have a preference for the magnetic poles it formed; (Which maybe why it require variable electromagnetic stress of kicking of the electromagnetic spring is necessary to generate a steady supply of electricity.) while Magnet is a hard spring since its magnetic polarity can’t be change easily and require great amount of energy. If we apply Hook’s law on spring here, we can easily see the spring of magnet is continually stressed by the generating coil(due to identical polarity with the magnet it facing), and as result the magnet also react back to the generating coil. This stressing back and fro formed the main mechanism of electrical generation, and would experience by the rotator as retarding force. Electrical generation is possible due to the continue competition of two electromagnetic stresses (and the kinetic energy from outside that keep the rotator rotating.)
However, as every spring has its elastic limit, so do magnet has its upper limit of tolerance of identical magnetic polarity, we could expect there is an upper limit of the electrical energy produced by each generating coil before it broke the spring of the magnet(demagnetize it). Thus, in a sense, we are extracting the spring energy from each magnet in the electrical generation process. The amount and the nature of electrical energy is depending on the nature of the magnetic field from each magnet. It is essentially a mutual induction process of an object that has unchangeable voltage and current interacting with another object that has changeable voltage an current. Magnetic energy from the magnet is transform into electrical energy from this inexhaustible supply of magnetic energy. It is not a conversion process as stated in classic electromagnetism!
It is thus impossible to use only two electromagnetic coils to produce electricity since there is no way to for one coil to extract spring energy from the another coil, how to expect a ’soft’ spring react to another ’soft’ spring?
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