This is a very simple circuit to build and there are only a handful of things that you will need to create it.
1. An LED of any color
2. A 9 Volt Battery
3. A 9 Volt Battery Clip
4. A Breadboard
5. A 1500 Ohm Resistor (1.5k)
Optional: A Voltmeter
LEDs are used everywhere in the world around us. Their versatility and reliability have made the usage of tiny incandescent bulbs as indicator lights obsolete. However, the high cost of large LEDs has disallowed them from making an impact in the general lighting market. This circuit is simply a power supply connected to a resistor, that limits the current that can pass through the LED to prevent damage from occurring. Unless you use an LED that can handle 9 volts, it is always necessary to include a resistor or the LED will likely be destroyed. LEDs are quite delicate, but can tolerate some reverse bias voltage (voltage applied in the wrong direction across the component) since they are a variant of the diode, which only allows current to flow in one direction.The LED has two leads, an anode and cathode. The anode must have positive polarity (+) and the cathode must have negative polarity (-) for the LED to allow current flow and output light. The cathode lead is shorter and is also indicated by a notch in the side of the plastic case. The inside of the LED is basically a small chip with a combination of semiconductors. Often, this chip is placed inside a plastic dome that helps to spread the pinpoint of light and magnify it. The color of the LED is dependent on the design of the chip, and some LEDs display different colors at different voltages. Common colors are red, yellow, orange, green, blue, and white.1. Connect the battery clip to the 9V battery
2. Connect the red lead of the clip to one lead of the resistor
3. Connect the black lead of the clip to the cathode of the LED (shorter lead)
4. Connect the other lead of the resistor to the anode of the LED (longer lead)
Congratulations, you should now have a lit LED! If it isn't working, try checking the battery, switching the LED around in case it is backwards, or replacing the LED.
The battery provides a voltage source, or a difference in charge. Since there are more electrons in one side of the battery than the other, there is a motivation for them to move from the negative terminal to the positive terminal. When the two terminals are given a path to connect through (the circuit) the electrons flow through the circuit. However, the resistor is a poor conductor and reduces the maximum amount of current flow through the circuit, keeping the current at a safe level for the LED. As current moves through the LED, electrons are turned into visible light energy.Congratulations! You have built a useful circuit that is implemented many places. You should now feel more comfortable with building electrical circuits and handling components. You now understand the operation of a simple LED circuit and can build your own!