- As discussed earlier, the electrons injected from emitter into the base constitute the emitter current(IE).
- Out of these electrons very few will combine with the holes in the thin base region to constitute the base current (IB).
- The remaining electrons pass through to the collector region and then to the positive end of Vcc to constitute the collector current(IC).
- Therefore we can write that,
- That means, emitter current is always equal to the sum of collector current and base current.
- As IB is very small compared to IE we can assume the collector current to be nearly equal to the emitter current.