The NPN transistor will be turn ON when the voltage difference is about and/or above +0.6V (voltage between the base and emitter, like: +0.6V, +0.7V, +0.8V, +0.9V, +1V, and +2V and so on...),

If you put 2V from base to emitter, the transistor will likely die a sudden death.

Bob

 

/*/QUOTE="pinkyponky, post: 1675910, member: 665778"]
Hi Ian0,
..........................
Below I have described as I understand, please correct me if I'm wrong.
[/QUOTE]
No - that is too simple.
It is by far not sufficient to characterize the BJT states with "on" or "off" - don`t forget that between these two terms the transistor can be used as an amplifier with a collector current Ic=f(Vbe) .
1.) The BJT is "off" when the collector current is zero (Vbe erqual or below zero volts)
2.) The BJT can be characterized as "on" (in the digital sense) when Ic is at its maximum and Vce is at its minimum. In practice, we require the B-C pn junction to be forward biased (Ib larger than anticipated according to the B-factor).
3.) For all Vbe values which enable an operational point (Ic, Vce) within the quasi-linear transfer region, the BJT operated between the extremas as mentioned in 1) resp. 2).