Wow! Your seedlings look very healthy. Usually sprouting acorns is done outside in a protected area so they are growing with the season. 

When growing any plants indoors under lights, you want to have your lights just above the plants so that they grow strong and not to tall and spindly. You also will want to put a fan on them at times to mimic a gentle breeze. This make them stronger. 

Since you have them indoors, I would set your lights to mimic regular daytime. It’s natural that they will drop some leaves but yours look very healthy - no chlorosis or wilting. As soon as you can, start to acclimate them to the outside beginning with very short times. 

When you transplant them in the spring be sure to protect them for the first 2 years at least. Some of them will not make it, but you have plenty. 

Here are a couple of articles that should be helpful. Also, there is an excellent book by Ken Druse Making More Plants that you can probably find at your local library.

https://www.thespruce.com/growing-bur-oak-5091583

https://www.extension.iastate.edu/news/yard-and-garden-handling-germinating-and-planting-acorns