- When you are not taking data, please disconnect the battery; this
will increase its lifespan.

- Connect the circuit shown above using the 1000-ohm resistor. Orient the
diode with its band closer to point B. Record this data under "Forward Bias".

- With the switch closed and the current flowing, adjust the potentiometer
until there is voltage of 0.05 volt across the resistor. Measure the voltage
across the diode.
*Record your values in the table below.*

- Adjust the potentiometer to attain voltages across the resistor between
0.10 volts and the maximum battery voltage. For each of these settings,
measure the voltage across the diode.
Take more data where the plot is interesting, less where it is predictable.*Record your values in the table below. Plot the points as you go.*

- Reverse the orientation of the diode. Record this data under "Reverse
Bias".

- Set the diode voltage (not the resistor voltage this time) to values
between 0.50 volts and the maximum battery voltage. For each of these
settings, measure the voltage across the resistor.
Take more data where the plot is interesting, less where it is predictable. (Sometimes zero is the correct answer.)*Record your values in the table below. Plot the points as you go.*

- Calculate the current flowing in this series circuit by dividing the
resistor voltage by the resistance.
This must also be the current flowing through the diode.*Record your values in the table below.*

Plot the forward bias voltages on the positive horizontal axis and the reverse bias voltages on the negative horizontal axis. This graph is called the current-voltage characteristic of the diode.*Graph the current through the diode (vertical axis) vs. voltage across the diode (horizontal axis).*

- Repeat the exercise with the 330-ohm resistor in place of the 1000-ohm
resistor.

*Discuss the shape of the graph. Describe in words how a diode behaves.*

*Plot the 1000-ohm and the 330-ohm graphs on top of each other. Is there any difference in the two curves? What does this tell you about the diode?*

*Sketch the current-voltage characteristic of a resistor and compare it to that of the diode. Does the diode obey Ohm's Law?*

*Suggest an application for a diode.*

Forward Bias

V_{diode} | V_{resistor} |
Current |

Reverse Bias

V_{diode} | V_{resistor} |
Current |

Forward Bias

V_{diode} | V_{resistor} |
Current |

Reverse Bias

V_{diode} | V_{resistor} |
Current |

- When you are not taking data, please disconnect the battery; this
will increase its lifespan.

- Connect the circuit shown above using R
_{1}= 1000 ohms and R_{2}= 100 ohms. Be sure that the transistor is seated properly in its socket.

- Adjust the potentiometer until the voltage across the large resistor
V
_{AB}is approximately 0.002 volts (=2 millivolts). Measure the voltage across the small resistor V_{CD}.*Record your values in the table below.*

- Adjust the potentiometer to attain voltages V
_{AB}between 0.000 volts and 0.250 volts.Take more data where the plot is interesting, less where it is predictable.*Record the corresponding V*_{CD}in the table below. Plot the points as you go.

- Note that V
_{AB}divided by R_{1}gives the current flowing into the base of the transistor I_{B}, while V_{CD}divided by R_{2}gives the current flowing out of the collecter I_{C}.*Record your current values in the table below.*

*Graph the collector current I*_{C}(vertical axis) vs. the base current I_{B}(horizontal axis).

- Repeat the exercise with R
_{2}=330 ohm instead of 100 ohm.

*Discuss the shape of the graph. Describe in words how a transistor behaves.*

This ratio I*Find the slope of the straight-line region near the origin.*_{C}/ I_{B}is referred to as the "current amplification" of the transistor.

This region is called "saturation" of the transistor.*What does the leveling off of the graph indicate?*

*Plot the 100-ohm and the 330-ohm graphs on top of each other. Is there any difference in the two curves? What does this tell you about the transistor?*

V_{AB} | I_{B} |
V_{CD} | I_{C} |

V_{AB} | I_{B} |
V_{CD} | I_{C} |

Bonus: "b" stands for "base"; "c" stands for "collector". What does "e" stand for on the transistor? (See why it pays to read the lab ahead of time?)

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