Exercise Three “Your First Circuit”. At this point we finally begin to make something that resembles an electronic circuit. The purpose of the experiment is to show you how to turn electricity into a functional property and power a light-emitting diode.
One of the key take-a-ways from this experiment is what is learned about the general properties of an LED. The longer wire (Anode) is the more positive side and the shorter wire (Cathode) is the negative side of the LED. More importantly, the voltage difference between the two leads must not exceed the manufactures recommendations. The current that passes through the LED must also not exceed the manufactures recommendations. If these precautions are not taken you will end up with a blown LED.
Exercise three is performed in three phases. You start with the highest resistor (2.2k) and subsequently replace the resistor in the circuit with the next lowest value. What should become visually obvious is as the amount of resistance decreases, the amount of voltage and current increases causing the LED to glow brighter and brighter.
Hopefully you can see the LED lit in the photograph, the resistor in the circuit is a 1K ohm resistor.
1.5v AA Batteries (4)
Four Battery Holder
470, 1K, 2.2K resistors