Light My First LED
Make a tiny light glow with a battery and a resistor.
What you’ll learn
- A circuit needs a complete loop to work.
- Why an LED needs a resistor friend.
- Which leg of an LED is positive (the long one).
- How current flows from + to − through every part on the way.
What you need
| Item✓ | Qty | ~Cost | Where to buy | |
|---|---|---|---|---|
| 9V battery + snap clip | 9V battery + snap clip | 1 | GHS 23.00 | Any supermarket or hardware store. |
| 220 Ω resistor | 220 Ω resistor Look for red-red-brown stripes. | 1 | GHS 0.75 | Electronics shop or online (Amazon, Adafruit). Look for red-red-brown stripes. |
| Red 5 mm LED | Red 5 mm LED Any colour works; red is brightest. | 1 | GHS 1.50 | Electronics shop or online. Any colour works; red is brightest. |
| Half-size breadboard | Half-size breadboard | 1 | GHS 23.00 | Online (Amazon, Adafruit, AliExpress). |
| Jumper wires | Jumper wires | 4 | GHS 30.00 | Online — usually sold in packs of 30. |
| TotalTotal | ~GHS 78.25 | |||
Build it step by step
Set the breadboard down flat
The long red and blue lines along the sides are your power rails. Red is +, blue (or black) is −.
Plug in the resistor
Push the 220 Ω resistor across rows e5 and e10. Each lead lands in its own column-strip.
Holes: e5, e10
Plug in the LED across the trench
Long leg (anode, +) into e12. Short leg (cathode, −) into f12. Crossing the trench keeps the two legs on different strips.
Holes: e12, f12
Bridge the rail to the resistor
Run a jumper from the top + rail to a hole in column 5 — say a5. That carries + into the resistor’s left lead.
Holes: +1, a5
Bridge the resistor to the LED
Jumper from b10 to b12 — same row in different columns. Current crosses from the resistor’s right lead into the LED’s anode.
Holes: b10, b12
Send the cathode home
Jumper from g12 to the bottom − rail. That returns current to the battery’s − side.
Holes: g12, -12
Hook up the battery
Battery clip’s red wire to the + rail; black wire to the − rail. Snap on the 9 V battery and watch the LED glow.
How it works
Electricity flows from the battery’s + terminal, through the resistor (which slows it down so the LED doesn’t burn out), through the LED (giving up a little energy as light), and back to the battery’s − terminal. A complete loop = a working circuit. Break the loop anywhere and the light goes out.
If something’s not working
LED doesn’t glow
- · LED is in backwards (long leg has to be on the + side).
- · Battery is dead — try a fresh one.
- · A jumper isn’t pushed all the way in.
LED is super dim
- · Resistor is way too big — 220 Ω is right; 10 kΩ would be too much.
Smelled something burning?
- · No resistor in the loop. Stop, unplug the battery, and add one.
Try this next
Swap the red LED for a green or blue one — same circuit works.
Touch the resistor after a minute. Is it warm? It’s doing its job.
Hold the LED close to your eye in a dim room. Try to spot the tiny glowing chip inside.