Camera obscura and electric fan: what they have in common

1. Step 1. Camera obscura — evolved into — Camera. A camera is a camera obscura with a light-sensitive layer.
2. Step 2. Camera — evolved into — Smartphone camera. A smartphone camera keeps the layout of a camera: a lens forms an image on a light-sensitive surface.
3. Step 3. Smartphone camera — is part of — Quadcopter (drone). A camera.
4. Step 4. Quadcopter (drone) — has part — Propeller. Air propellers.
5. Step 5. Propeller — is part of — Electric fan. The blades.

Open Evothings