Hi,
AFAIK there's no such option in AC3D.
You can add a light but it's a very limited feature, not intended for that purpose.
You will have an emitting light bulb effect by using a renderer, or a 3D engine.
If you are using PovRay the following link can help you :
http://tag.povray.org/povQandT/languageQandT.html
HTH.