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### Course: Class 12 Physics (India)>Unit 14

Lesson 8: Transistors working

# Parts of a transistor

We will see the names of the different parts of a transistor. We will also explore some aspects related to the design of a practical transistor.  Created by Mahesh Shenoy.

## Want to join the conversation?

• So basically forward biasing means you're applying a voltage to allow flow of electrons in a transistor, and reverse biasing means you're applying a voltage to prevent the flow of electrons in a transistor?
• No, forward biasing means we are connecting positive terminal to p and negative terminal to n of PN diode/junction. In reverse biasing we switch the terminals of the battery. The terminal to which p and n terminal attached plays a key role in deciding flow of current. There is will be flow of current in both cases but less (micro amperes) in Reverse biased PN junction compared to Forward biased ( in milliampere).
• For N-P-N transistor, the electrons are minority charges in the base region, but in collector region they are majority charges, then how they reach the collector's terminal while reverse-biasing?
(1 vote)
• Electrons from the p reaches the depletion region by diffusion, there it gets attracted by the exposed positive ions on the n side of the depletion region and thus the electron gets sucked towards the n side.
• So, let me get this straight... The ampification is primarily
dependent on the relative doping of the emitter over the base.
Am I right?
(1 vote)
• Not relative but yeah it needs to heavily doped to generate a large number of electrons and base needs to lightly doped for less recombination to occure.
(1 vote)
• How is it that reverse bias aids the flow of electrons. At the junction b/w p&n in reverse bias won't the depletion layer increase?

Thanks for the video
(1 vote)
• At the reverse bias, the movement of minority charge carriers is supported. And at that junction, the electrons ARE the minority charge carriers (it's a p-type semiconductor), and hence they are swept across to the collector.
It's all explained in the previous video, go check it out!
Hope that helped!
(1 vote)
• if doping changes the conductivity of a material, is he saying the electrons "literally jump" from the wire to the base, practically skipping over the emitter, because the emitter is highly doped? In that case do we consider the base where the current enters the BJT?
(1 vote)