Why does small base current control large collector current in a BJT?

[nullk8]

trying to figure out the meaning of lattice struction in semiconductor...
and, why a small current in the base circuit of a transistor can control a large current in collector part when "bipolar junction transmission" happened?
Thanks for any help!

 

[chroot]

I'm not sure what you mean by "lattice struction," but here's a description of the operation of a bipolar junction transistor:

http://en.wikipedia.org/wiki/Bipolar_junction_transistor

- Warren

 

[kurious]

The small current stops negative charge from sitting still on the base ( p part of npn
junction).