The transistor has a current amplifying effect, and its essence is that the transistor can control the large change of the collector current with a small change of the base current. This is the most basic and important characteristic of the triode. We refer to the ratio of ΔIc/ΔIb as the current magnification of the transistor, represented by the symbol "β". The current magnification is a fixed value for a certain triode, but it will also change with the change of the base current when the triode works.