The LED, our tiny light
Light Emitting Diode — only goes one way, glows when it does.
Read first: The mighty resistor
LED stands for Light Emitting Diode. "Diode" is the important word — it means electricity can only flow through it in one direction. Plug it in backwards and nothing happens at all.
You can tell which way is which by looking at the legs. The long leg is the positive side (called the anode). The short leg is the negative side (called the cathode). Long for plus, short for minus.
Why always with a resistor
Without a resistor, an LED takes more current than it can handle and burns out in a fraction of a second. The resistor sets the limit. For most beginner LEDs, a 220 Ω resistor is the right safety net.
You plug an LED in backwards. What happens?
Now you understand…
- LEDs only glow when current flows through them the right way.
- Long leg = positive (anode). Short leg = negative (cathode).
- Always pair with a resistor, every single time.
Now learn to control when the LED is on.