TRANSISTOR FORMULAS
V. Ryan © 2002
Transistors are used to amplify current and so in an examination you could be asked to find the BASE current or COLLECTOR current or the GAIN. The GAIN is simply the amount of amplification. The formulas and example questions are set out below: 

A simple way of remembering the formula is seen in the diagram opposite OR you can learn each of the formulas below. 

Another very important point to remember is that collector current is always greater than base current, sometimes by many times. 



TRY THE FOLLOWING QUESTIONS:  
1. If the collector current of a transistor is 0.12 amps and the gain is 40, what is the base current?  
2. If the collector current of a transistor is 0.4 amps and the base current is 0.002 amps, what is the current gain? 

3. If the collector current of a transistor is 0.5 amps and the gain is 100, what is the base current?  
