Q:

Misunderstanding of amplifiying a current with transistor

Electrical books say that we can use transistor to amplifying current but when I simulate a circuit in proteus input current, it is smaller than emitter current but why?  
This is a common collector and we expect that the current to be amplified at the emitter point.

A:

You appear to be comparing the current supplied by the battery to the current from the transistor's emitter.  This is incorrect.
Some of the current from the battery will flow through the potentiometer, so the emitter current must be less than the battery current.
The gain of a transistor in this circuit is the ratio of the emitter current to the base current. 

