Electronics - Bipolar Junction Transistors (BJT) - Discussion

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.

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.

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.

Due to forward wise both junction, it behave low resistance.

When the positive probe of ohmmeter is placed on the p-type base in the transistor, it makes the condition of forward bias and we know that in forward bias resistance is low. That is the reason for the low resistance.

It is required to obtain resistance b/w emitter and collector. How do you do that?

No @yadhunanda it is rite ! low resistance between both emitter and base as well as base and collector since emitter and collector both will have the negative terminals of the probe ! and hence it will always make a forward bias circuit.

Here question is not correct if positive terminal is there on the base of npn transistor low resistance between base and emitter terminals, high resistance between collector and base.

Electrons are attracted towards the +ve terminal of the battery. And as base is p-type, which is connected to +ve of battery.

But the question is that they ask that if p terminal of supply is connected with p terminal of npn transistor what should be the reading of ohm meter with other two terminals not only for emitter terminal.