How Do NPN Transistors Function in a Circuit?

[sanado]

Hey guys, i was wondering if you would be able to help me. I am currently in year 12 and am about to start learning about electronics. Part of the course is NPN transistors. I had read about 5 different books on how they work and yet i still dun understand them and how they work in a circuit. For example:

What does the base, emitter and collector do and how are they all related?
When a NPN transistor is used in a circuit, are the charge carriers positive?

Any help you can offer will be most appreciated.

 

[member 553083]

Thanks in advance.In an NPN transistor, the base is the control element of the transistor. It is used to control the flow of current between the emitter and collector. The emitter is where electrons enter the transistor and the collector is where they exit. The emitter and collector are connected by a very thin layer of semiconductor material known as an ‘active layer’. When a voltage is applied to the base, this causes the active layer to become thinner and allows current to flow between the emitter and collector. When a NPN transistor is used in a circuit, the charge carriers are electrons (negative) and not positive.