Transistor Lab

 

Construct circuit a) and answer questions. Then modify it to make circuit b) and answer the questions.

Use the following table to record your data:

1. Is the LED on when the switch is open or closed in each circuit? Why?
2. For each circuit measure the voltages across the resistors when the the switch is closed and when it is open.
3. Use Ohm's Law to calculate currents through the base, I_b, and throught the collector, I_c.
4. Compute the ratio I_c/I_b, called the amplification factor. What does this tell you about transistors?
5. A perfect transistor switch would have a collector-to-emitter voltage V_ce of zero. Measure V_ce for your transistor when it is on.

	Circuit a)			Circuit b)
Switch	Open		Closed	Open		Closed
LED
V across 220 W
V across 10k W
Ib (mA)
Ic (mA)
Amplification factor
Vce

Summarize in words what you discovered about transistors: