Vacuum tube e railway semaphore: o que têm em comum

1. Passo 1. Vacuum tube — evoluiu para — Diodo. The first diode was a vacuum tube (Fleming); later diodes became semiconductor devices.
2. Passo 2. Diodo — inclui — LED. A light-emitting diode.
3. Passo 3. LED — faz parte de — Traffic light. LEDs.
4. Passo 4. Traffic light — evoluiu de — Railway semaphore. The first traffic light was a railway-style semaphore.

Abrir Evothings