Motional EMF is just a direct application of the definition of the magnetic field. This definition states that a charged particle moving in a suitable direction in a magnetic field experiences a magnetic force. The free electrons in a conductor moving in a suitable direction in a magnetic field experience a magnetic force, which constitutes an emf in the conductor, the motional EMF.

When the magnitude of a magnetic field changes with time, it produces an electric field. A closed path suitably oriented in this electric field has an emf, the transformer emf. This closed path may or may not be conductive. The magnitude of the emf is a function of the time rate of change of the magnetic flux linking the closed path. This is given by one of Maxwells classic four laws. This law is sometimes called Faradays Law. This law utilizes a partial derivative, which has the effect of eliminating the effect of motion. The relevant rate of change of the magnetic flux linking the closed path is purely a function of the change of the magnetic field itself and is not a function of any change of flux linking the closed path due to motion of the closed path causing a change of orientation within the magnetic field or changing the size or shape of the closed path.

Between them, motional emf and transformer emf cover all the cases. Now we come to the pseudoscience. There purportedly exists another principle, also called Faradays Law. It is the relevant one of Maxwells Laws with the partial derivative changed to the ordinary derivative, and it only applies to circuits. This version of Faradays Law implies that the rate of change of the flux linking the circuit is the only thing that counts, regardless of the cause. It supposedly includes both motional emf and transformer EMF in circuits. This version of Faradays Law is false! Richard Feynman, in his Lectures on Physics, pointed out that this version of Faradays Law does not always work and gave two examples of this fact, although he called it the flux rule. Motional EMF and transformer emf are independent principles. For them both to be included in a single term of an equation is logically impossible. In every case where the flux change is solely due to motion, the motional emf is the total emf. There is nothing left for the flux change to account for. If the flux change due to motion had an effect, it would add to the motional emf and give twice the value of the actual emf. All flux change is not created equal. Only a changing magnetic field creates an electric field. The changing orientation of a circuit with respect to the magnetic field does not. In most cases of motional emf there is an accompanying flux change. This is a case of correlation, not causation. It is guilt by association. The flux change is just along for the ride. It has no effect. The Faraday disk dynamo is a case where there is no flux change in the circuit, so the flux change and motional emf are effectively separated, and the faulty version of Faradays Law fails completely. The faulty version of Faradays Law specifies no emf, but of course there is one. Virtually every textbook and encyclopedia contains egregious conceptual and factual errors regarding the subject of induction. It would seem that the authors do not understand this part of elementary physics, as simple as it is. It is an indictment of the status quo and a scandal.

Mike