7.3. Working Principle

Try these first

1. 1.

   What are the three terminals of a BJT?

   Hint

   Think about the structure of the transistor.

2. 2.

   What happens at the emitter-base junction in an NPN transistor?

   Hint

   Consider the biasing type.

3. 3.

   What is the function of the emitter-base junction in an NPN transistor?

   • It blocks current flow
   • It allows current to flow from collector to emitter
   • It allows current to flow from emitter to base

   Hint

   Think about the biasing direction.

4. 4.

   True or False: The collector-base junction in a BJT is forward biased.

   • True
   • False

   Hint

   Recall the definitions of junction biasing.

5. 5.

   If the base current (I_B) of a BJT is 10 mA and the current gain (β) is 100, what is the collector current (I_C)?

   Hint

   Use the relationship between base current and collector current.

6. 6.

   Explain how changing the biasing conditions on the collector-base junction could affect the operation of a BJT in a circuit.

   Hint

   Consider the impact of reverse bias on current flow.