Inductor EMF direction

Question

I have some serious troubles with understanding the EMF in inductor.
Assume we change the current from value $I_0$ to zero by rotating the tumbler of the source.
Then why should we consider the EMF induced by inductor would act like on the right picture and not like on the left one?
There are opposites cases of electric potentials distribution and they seems result in the similar current flow. But the first one is not realized in life

Or why do not we consider the case when the current is induced like in the 3rd bottom figure?

Ján Lalinský · Accepted Answer

Do not use plus/minus signs to show direction of electromotive force or induced current. They will mislead you. Also, electromotive force is an independent force in the circuit that isn't captured by the concept of potential; EMF in an inductor isn't necessarily directed from terminal with higher potential (+) towards the terminal with lower potential (-).
The correct direction of EMF can be denoted by an arrow parallel to the component (inductor) and can be derived from the Lenz law: its direction is such that current contributed by this EMF is in direction that counteracts(but not completely) the change of current that is actually happening.
So if current is going from top to bottom, and decreasing in time, EMF has to point upwards.

Inductor EMF direction

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