Can we interchange emitter and collector?

No, we cannot interchange emitter and collector of a transistor due to following reasons: (i) In a transistor emitter is heavily doped and collector is comparatively lightly doped. (ii) In a transistor, the contract area of emitter- collector junction is larger than that of emitter- base junction.

What happens if you connect a transistor in backwards?

Yes current can flow in both directions. An NPN transistor backwards is also an NPN. There will still be a reverse beta, however, the backwards NPN transistor won’t work as well as a correctly oriented one will. It’s not recommended.

Can we interchange the source and drain terminals in a FET circuit can we do the same with the emitter and collector terminals of a BJT circuit?

Theoretically you should not. The doping of base, emitter and collector all are different, with emitter being the most doped. But although emitter is more doped than collector, width of collector is more than emitter so total number of charge carriers remains almost same in both emitter and collector.

What will happen if transistor is not biased properly?

If the transistor is not biased appropriately, it may lead to the poor amplification of the signals resulting in the gain being very low.

Why can’t we interchange the emitter and collector eventhough they are made up of same type of semiconductor material?

We need emitter doping to be highest, while in reality collector doping is less than emitter doping. Hence we can not exchange emitter and collector. Because emitter is highly doped region and collector is moderately doped.

What does the notch on a transistor indicate?

As the collector of a transistor has to dissipate much greater power, it is made large. In a Practical transistor, there is a notch present near the emitter lead for identification. The PNP and NPN transistors can be differentiated using a Multimeter.

Do transistors work in reverse?

A transistor in reverse active mode conducts, even amplifies, but current flows in the opposite direction, from emitter to collector.

Can current flow from emitter to collector?

In active and saturation modes, current in a PNP flows from emitter to collector. This means the emitter must generally be at a higher voltage than the collector.

Why can’t we interchange the emitter and collector even though they are made up of the same type of semiconductor?

Will a BJT still work if we interchange its collector and emitter terminals?

No. Transistors are designed to provide the optimum performance when they are correctly connected. Interchanging the collector and emitter terminals not only degrades the transistor performance but also might cause permanent damage to the device.

What happens if base-emitter junction is reverse biased?

The base-emitter junction behaves like any other PN junction when viewed alone. If the base-emitter junction is forward biased, the transistor is on. If it is reverse biased, the transistor is off. This is just like a diode.

Why are collectors reverse biased?

Collector is always reverse-biased w.r.t base so as to remove the charge carriers from the base-collector junction.

Why can’t we change the position of the emitter and collector?

We cannot change their positions because doping concentrations are different for emitter , collector and base . This is how it is providing current due to to charge carriers also known as BJT (bipolar junction transistor)

What is the difference between emitter junction and collector junction?

The emitter junction has the function to have high injection efficiency to make the forward current amplification factor high. The collector junction has to withstand the breakdown voltage of the transistor which dictates that its bulk must be relatively low doped.

Why can’t we use a doped emitter as a collector?

There is one more reason, emitter being heavily doped (acting as collector now) will have a very low breakdown voltage, so you can not operate it at higher voltage level. If the npn transistor is symmetrical in construction its forward and inverse operation will be identical.

Should I doping the emitter and collector of a solar cell?

Theoretically you should not. The doping of base, emitter and collector all are different, with emitter being the most doped. But although emitter is more doped than collector, width of collector is more than emitter so total number of charge carriers remains almost same in both emitter and collector.