The electromagnet glass is usually used in conjunction with the Electromagnet Blocks.
Electromagnet glass has less durability than regular glass, making it dangerous to mine around it when part of an active reactor. Electromagnet glass can be broken and picked up again.
The primary use for electromagnetic glass, is to be able to observe a particle accelerator or Fusion Reactor while they are on. A simple mistake that can be made is that electromagnetic glass does not transfer heat like regular electromagnets. You will need to use as combination of the two to make a functional fusion reactor. Use normal electromagnets below where you would put the water.
Electromagnetic Glass does not transfer heat like normal electromagnets
Electromagnetic glass can be broken VERY easily so don't be mining around your reactor!