Why a transistor stops working if we interchange the emitter and collector?

Why a transistor stops working if we interchange the 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 is collector current when transistor is off?

The transistor is off when there’s no bias voltage or when the bias voltage is less than 0.7 V. The switch is on when the base is saturated so that collector current can flow without restriction. This type of LED has a voltage drop of 1.8 V and is rated at a maximum current of 20 mA.

What is the relation between base-emitter current and collector emitter current in a bipolar transistor?

What is the relationship between the base-emitter and collector-emitter voltages of a bipolar transistor? Generally, the current that flows from the emitter to the collector or vice versa is the base current times the DC current gain (hFE). Note, however, that hFE varies with the collector-emitter voltage (VCE).

When the transistor is turned off the voltage dropped across the collector emitter junction is?

The transistor keeps lowering the voltage drop across the collector emitter junction (increasing the voltage drop across the 100Ω resistor and thus increasing the current) until the transistor saturates (i.e. can’t lower the voltage any more) at about 0.2V.

What happens when you use transistor in reverse?

Now, if you use the transistor in reverse, the emitter becomes the collector and the collector becomes the emitter, and its quite simple to see what happens: (1). As the collector doping is less than the emitter doping, the hole current in the collector (now the emitter) increases, leading to lower beta.

Why do you not get current amplification in a transistor?

You won’t get the current amplification feature of the transistor because you’ve not connected the collector. In this configuration you have a silicon PN junction and it does all what a PN junction does: rectification, about 0.7v voltage drop and so on. It’s not much different to what a vanilla diode like the common 1N4184 diode would do.

Why does the emitter have a low breakdown voltage?

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. This has to do with the operation of the transistor. Let me explain again what the operation of the transistor is:

Why does the transistor conduct more current than the base?

Because of that 0.3mA base current, the transistor will be pretty strongly “on”, meaning the collector will conduct (a lot more) current than the base. If you then connect a voltage source between the collector and the bottom of your existing 5V source, then additional current will flow through the collector and the LED.