Hard to say as all detectors are different. I only know that while as a teenager I got kicked out of public school for skipping class too much and was sent to an "alternative placement center".

Everyone there had to wear a white shirt and pants. There was only one entrance and there was a metal detector right in front of it. But what all the "cool" kids were doing was seeing how big of a knife they could sneak through it. And there was a couple of 3 inchers that got through. It mattered were the knife was and how you held your hands as you went through, but can't remember the details (this was back in 2001).