In the classic version, the power coming from an electrical outlet reaches the bulb emitting the light. A switch usually intervenes between the power source and this point of light for ignition and extinguishing functions.
But in modern touch models, this current breaker disappears from the circuit. Before you buy such a model, you must understand how this stuff works in order to use it as intended. In this configuration, your body acts as a switch. The human body is a good conductor of electricity.
The product contains a transistor, otherwise known as a magnetic amplifier. It is connected to a metal sensor, which in most cases is in the base of the lamp. Until then, the generated current flows through the loop without reaching the lamp. But as soon as you touch your equipment, that current reaches the ground through your body.
Thus, the circuit closes and the lamp lights up. Depending on the amount of pressure or the number of strokes, you increase the glow and eventually stop the circulation of electricity again. This last step causes the light to turn off.