Q. I was using my soldering gun and happened to get a screwdriver blade close to the tip while it was on. The screwdriver started vibrating. When I cut the soldering gun off, the tip stopped vibrating. What happened?
A. The body of the soldering gun contains a big step-down transformer. It steps the primary voltage down and the current up. The high AC current passes through the copper tip to heat it. When current passes through a conductor, it produces a magnetic field around it.
The screwdriver blade must have been made of steel. THe magnetic field alternated, because the current in the tip is AC. The alternating magnetic field attracted the blade of the screwdriver, which made it vibrate.