Скачать или смотреть How Transistor Works? ট্রানজিস্টর কিভাবে কাজ করে? II Gobeshona

NPN:
There is thin P-type material in the middle of N-type material forms sandwich is called NPN transistor.
PNP:
Thin N-type material in the middle of P-type material which form sandwich is called PNP transistor.

Thin middle layer is called Base(B). The layer which collects current is called Collector(C). The layer which provide output current is called Emitter(E).
Emitter is heavily doped and becomes wider. Majority carrier free electrons are more here.
Collector is also wider but smally doped. So, free electrons are less here.
Base is thinner and lies in between emitter and collector. It is slightly doped and majority carrier holes which are less here.
If we connect battery in between emitter and collector then what happened?
Negative terminal of battery connected to emitter.
Emitter-base junction becomes forward biased and base-collector junction becomes reverse biased. In this condition there is no current flow through this device. Entire voltage applied in emitter & collector is dropped in two places. Forward barrier potential across emitter-base junction which is 0.7 volt in case of silicon transistors. The rest portion of the applied voltage is dropped as a reverse barrier across the base-collector junction. Because of 0.7V fixed voltage collector voltage cannot overcome forward barrier. Ideally free electron cannot cross forward barrier potential to base.
So, transistor works then as a OFF switch.
Transistor cannot conduct current. No voltage drop in external resistor, because entire voltage drop in junction.
If we apply positive voltage to the base, then what will be happened?
Base-emitter junction got forward voltage which overcome the forward barrier potential. So, majority carrier free electron from emitter region cross the junction and enter into base region, where they got less hole for recombination. Due to electric field of junction free electrons got kinetic energy. Base region is so thin that, free electrons come from emitter region cannot get enough time for recombination so that they cross the reverse biased depletion region into collector region.
In base-collector junction there is reverse barrier despite free are not obstructed. In base region free electrons are minority carrier. In this way, electron migrated from emitter to collector. Thus current flows from collector to emitter. There is less amount hole in base region and free electrons come from emitter recombined with those hole and draw small current. This base current is much smaller than collector to emitter current.
So, during migrating free electrons from emitter region to collector region contributes small base current and rest major portion contributes collector current.
Emitter current = Base current + Collector current

=====================

Subscribe our Channel:
   / gobeshonadotcom  

=====================

www.gobeshona.com একটি টেকনোলজি বেইজড অনলাইন ই-লার্নিং প্ল্যাটফর্ম। আমরা শুধুমাত্র ইলেক্ট্রনিক্স এ নতুন অথবা বিজ্ঞান বিষয়ে যাদের আগ্রহ আছে তাদের সাহায্য করার জন্য অনলাইন প্ল্যাটফর্ম তৈরির জন্য কাজ করে যাচ্ছি যাতে করে বাংলাদেশের যেকোনো প্রান্ত থেকে ঘরে বসেই ছাত্রছাত্রীরা শিখতে পারে।


আমাদের ওয়েবসাইট:
www.gobeshona.com

ফেসবুক পেইজে লাইক দিয়ে আমাদের লেটেস্ট আপলোড করা ভিডিওগুলো দেখতে ভুলবেনা।
  / gobeshonadotcom  
----------------------------------------------------------------------------
#Transistor
#Gobeshona
What is the basic function of a transistor?
How does a BJT transistor work?
What is transistor and its types?
transistor working principle
types of transistor
uses of transistor
transistor working animation
transistor as a switch
who invented the transistor
transistor diagram
npn transistor
types of transistor
how transistor works
uses of transistor
transistor working principle
pnp transistor
transistor? - definition in electronics
transistor as a switch
transistor in computer