so my question is regarding the diode used across the relay coil. My A level textbook (the section from the textbook is given below) says that its purpose is to protect the op-amp from a back emf induced when the current in the coil is switched off. But this explanation is not adequate enough for me. I don't understand how this will protect the om-amp.
My problems are:
1)I don't understand, how the emf is induced in the relay coil when the current is switched off.
2)I can't visualize how the current will be moving in the flyback diode when the current in the coil is switched off.
3)I don't understand how the diode will protect the op-amp, given that the first diode will stop any current from flowing back to the op-amp.
Please explain in layman terms. My qualification is just UK Cambridge international A level physics. Hence I don't understand the other complicated explanations given about flyback diode in this site.
thank you very much!