9.2.2. Polarity Changes in Current and Voltage

Try these first

1. 1.

   What type of materials are used in an n-p-n transistor?

   Hint

   Think about the order of layers in the transistor.

2. 2.

   What is the meaning of forward bias in a transistor?

   Hint

   Consider the implications for both the base-emitter junction.

3. 3.

   What is a key difference between an n-p-n and a p-n-p transistor?

   • Both have the same configuration
   • Material arrangement is different
   • Only one is used for amplification

   Hint

   Think about the arrangement of materials.

4. 4.

   True or False: In a p-n-p transistor, the emitter must be at a lower potential than the base.

   • True
   • False

   Hint

   Recall the requirements for forward bias.

5. 5.

   Analyze a given n-p-n transistor circuit where the base-emitter voltage is set at 0.7V and the collector-emitter voltage at 5V. Calculate the expected collector current if β = 150.

   Hint

   Remember to establish the base current using the supply voltage and the base resistor.

6. 6.

   Given a p-n-p transistor with an emitter current of 2mA, calculate the base and collector currents if β is known to be 100. Discuss what happens if the base-emitter voltage is lowered.

   Hint

   Relate the changes in base current to the effects on collector current.