How to explain mutual inductance with the image I attached? There are two conducting frames, one has a source of DC and a variable resistor, the other just a galvanometer. What I should conclude from this picture that the flux is F1=alpha*I and F2=c*F1, and Ein=-M*dI/dt. How? Is the current I, the induced current in the left frame or the changeable current in the right frame? Is F1 the flux for the left or the right frame?