Home >> Science & Nature >> Science

How to Make Two Lights Light Up With AA Batteries on a Breadboard

Demonstrate and explore scientific principles by building simple circuits with light-emitting diodes (LEDs). Domestic batteries produce low voltages that are safe to work with as long as you take elementary precautions. Use a breadboard to assemble your circuit tidily and with fewer opportunities for loose connections to spoil the effect of your experiment.

Things You'll Need

Single-core insulated copper wire, known as bell wire or breadboard jumper wire
Wire cutters and strippers
Solderless breadboard, also known as a microdeck, prototype board, protoboard or plugboard
2 LEDS
2 220 ohm, 1/4-watt resistors
2 AA batteries
1 AA battery holder
4 leads with alligator clips, also known as crocodile clips or croc clips

Instructions

Flashlight Bulbs In Series
- 1
  Cut five or six pieces of wire around three or four inches long. Strip away approximately half an inch of the insulation from each end of each piece.
- 2
  Plug the bare end of a section of wire -- preferably red -- into one rail of the breadboard. The rails are groups of five holes arranged along the sides of the board. All the holes in a group of five are connected in a row. There will be a red stripe running along next to one rail. Use this as your positive rail.
- 3
  Plug the bare end of a small section of wire -- preferably black -- into a rail on the other side of the breadboard. There will be a black stripe running along next to one rail. Use this as your negative rail.
- 4
  Push the long lead of one of the LEDs into the positive rail. This is the anode, or positive lead. Plug the short lead, known as the cathode or negative lead, into one of the other holes in the board -- not one of the holes on the positive rail. Note that the holes in the main part of the board will be connected horizontally, typically in groups of seven.
- 5
  Plug one of the leads of one 220-ohm resistor into one of the holes in the same row as the cathode of the LED so that they are connected. Connect the other lead of the resistor to the negative rail; you may need to connect it to one of the other rows of holes on the board and then connect that row to the negative rail with a piece of wire. Repeat for the second LED and resistor.
- 6
  Put the batteries into the battery holder. Clip one end of one of the alligator clip leads to the positive terminal of the battery holder. Clip the other end of the lead to the bare end of the red wire connected to the positive rail of the breadboard. Clip one end of the other alligator clip lead to the negative terminal of the battery holder. Clip the other end of the lead to the wire connected to the negative rail of the board. Both your LEDs should now light. The LEDs are said to be connected in parallel.

Science