A handheld Tesla coil is used to light fluorescent lamps without direct electrical connection. The Tesla coil generates a high-frequency alternating current at a high voltage, which creates a strong electric field around the coil. When a fluorescent lamp is brought close to the coil, the electric field ionizes the gas inside the lamp, causing it to glow. This demonstration showcases the concept of wireless energy transfer, the operation of Tesla coils, and the behavior of gases in electric fields.