How Do Bullet Trains Go So Fast?
Using aerodynamic shapes and often magnetic levitation to eliminate friction.
How Do Guitars Amplify Sound?
Using an acoustic sound hole to resonate air, or electric pickups that sense string vibrations magnetically.
How Do Vending Machines Detect Fake Coins?
Using electromagnets and light sensors to check the size, weight, and metallic composition.
How Does a Metal Detector Work?
Inducing a magnetic field and sensing the distortion when it hits metal.