Electricity & Magnetism


The word TRANSISTOR is a shortened form of transfer resistor, so named because it transfers an electrical signal from one circuit to another. In this exhibit, visitors are instructed to hold the two knobs on the board. A tiny current flows across the user’s body, completing the circuit from a battery through an emitter and base of a transistor. This controls a much larger current flowing through the emitter and collector to a lamp. Relaxing the grip increases the resistance. This reduces the current through the base, which also reduces the large current passing through the collector and light. In this way, a transistor amplifies the base current.