Electronics - Bipolar Junction Transistors (BJT) - Discussion

As we connect a Positive terminal on the base of NPN which is P-type so it reflects that it's forward biased.

So resistance is low.

Base connected the +ve terminal it's forward biasing condition. Collector base depletion region is high similarly emitter-base depletion region is low compared to CE. So, it's low resistance.

The correct answer is: "low resistance".

Explanation:

An NPN transistor has two PN junctions:

1. Base–Emitter (BE) — behaves like a diode (P to N)
2. Base–Collector (BC) — also behaves like a diode (P to N)

When you place the positive (red) probe on the base of an NPN transistor and touch the negative (black) probe to either the emitter or collector:

* You are forward-biasing the BE or BC junction.
* This gives a low resistance reading (just like a forward-biased diode).

So, the reading between base and emitter or base and collector will show low resistance.

Note:

* Reversing the probes would show high or infinite resistance because the junctions would be reverse-biased.