Basic principle
As we know, Electromagnetic wave can travel through air and insulated object. So electromagnetic technology is just realized by adopting a special pen that can send electromagnetic waves and receiving coil coating vertically and horizontally in the whiteboard. When the pen gets close to the coil coating, the coil would detect the electromagnetic waves sent by the pen. The induced electromotive force would be higher when the pen closer. According to the electromotive force vertically and horizontally, the pen's exact position can be decided by calculation.

Technical Advantage
1. Exact position, higher precision.
2. Fast response.
3. Special pen supports the right button function, which is convenient for control to the computer.
4. Competitive Cost.

Disadvantage
1. You must only use the special pen for any operation on the whiteboard. Finger or other stuff is not available.
2. The special pen needs to be replaced after a period.
3. External power supply is needed.