Why wont this LED light up when in series? (very simple)


The first LED wont light up. When placed in parallel however, they both light up.

The blue wire is connected to 5V on the arduino, and the grey wire goes to ground obviously.

edit: yes i double checked that they were inserted with the proper leads. In order it should be cathode - anode - cathode - anode, correct?


The problem is you don't understand how the Breadboards work... The top LED is shorted out.

I'll get a diagram...

Look at the http://ArduinoInfo.Info WIKI HERE: http://arduino-info.wikispaces.com/YourDuinoStarter#L3

The short breadboard sections (ABCDE, vertical in your photo) are all connected together.

See what's INSIDE a Breadboard: (This is part of the slide set Arduino101 Here: http://arduino-info.wikispaces.com/mao)

Use separate strips for each individual connection.

Ah, that was foolish of me. Thank you for the quick help!