Assuming it's configured on active mode. What exactly determines the amplification that you'll get from the base current into the collector current?

Is it the Beta parameter in the transistor or is it determined by the specific Votage source and resistor that you choose to put in the collector?

Thanks

 

Both.

We usually consider a common-emitter amplifier with regards amplifying an AC signal applied to the base of the BJT. To determine the voltage gain, it is instructive to examine the characteristic curves of the transistor, in particular, how the voltage at the collector traverses along the load line.

If beta, Vcc or RL is changed, the amplification will change.

For full explanation, see this:

http://www.electronics-tutorials.ws/amplifier/amp_2.html

 

I'll give it a read, thanks a lot.