Current location - Training Enrollment Network - Books and materials - Excuse me, what is the basis of the magnetic detector at the entrance of the library to identify whether the book belongs to the library?
Excuse me, what is the basis of the magnetic detector at the entrance of the library to identify whether the book belongs to the library?
Look at this book. Are there always so many pages stuck together (near the spine)? Take a closer look. Is there a long metal bar in those pages?
Yes, that's it. That's a metal strip. Of course, there are many magnetic strips that are more hidden and difficult to find. But you don't want to be a gentleman to ask this, do you?