In this experiment, the right LED in the collector path is brighter than the left LED in the base path because the base current is amplified by the transistor. In other words, a smaller current is used to control a larger current. The term "amplified" is misleading and does not amplify an electrical current(Go to Figure 4 and read text below). Remember, in experiment #14 the transistor was used as a switch. Here, it is still functioning as a switch, and in this sense the transistor is used as an amplifier. This is called current gain. Current gain by a transistor can vary anywhere from 10 to 1000 depending on the type of transistor. But, battery voltage and circuit resistance will limit the current gain. The circuit resistances, not the transistor itself, are limiting the current and the transistor is said to be saturated.
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| Current at base |
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| Current at collector (about 10x base) |
Current Gain
Thank you University of Virginia for information that helped me come to an understanding of this experiment.
Thank you University of Virginia for information that helped me come to an understanding of this experiment.
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