Your First Circuit - LED with Battery

What You Need

• 9V Battery
• LED (any color)
• 330Ω to 470Ω resistor
• Breadboard or alligator clips

Let's Build!

Here's what a real breadboard circuit looks like:

A simple LED circuit on a breadboard - great for prototyping

Circuit Diagram

[Battery +] ----[Resistor]----[LED]----[Battery -]

Step-by-Step

Step 1: Identify LED Polarity

• Long leg: Anode (+)
• Short leg: Cathode (-)
• Flat side: Cathode (-)

Step 2: Calculate Resistor Value

Using Ohm's Law:

R = (Vbattery - Vled) / Iled
R = (9V - 2V) / 0.02A
R = 350Ω

Use nearest standard: 330Ω or 470Ω

Step 3: Connect the Circuit

1. Connect resistor to battery positive 2. Connect resistor to LED anode (long leg) 3. Connect LED cathode (short leg) to battery negative

Step 4: Test

The LED should light up!

Troubleshooting

LED Doesn't Light?

• Check polarity (LED only works one way)
• Check connections
• Try new battery

LED Very Bright?

• Resistor too small
• Use higher value resistor

LED Burns Out Immediately?

• No resistor!
• Resistor value too low

Safety Tips

• Never connect LED without resistor
• Don't touch LED while it's on (gets hot)
• Remove battery when not in use

Summary

You've built your first circuit! This is the foundation for all electronics projects.

Next Lesson

In the next lesson, you'll learn how to use a multimeter to measure voltage, current, and resistance.