Balance pans and solar panel: what they have in common
- Step 1. Balance pans — is part of — Balance scale. For the load and weights.
- Step 2. Balance scale — evolved into — Electronic scales. Electronic scales.
- Step 3. Electronic scales — has part — Liquid-crystal display. The reading is on an LCD.
- Step 4. Liquid-crystal display — is part of — Electronic calculator. An LCD display.
- Step 5. Electronic calculator — has part — Solar panel. Many run on a solar cell.