Android and voltaic pile: what they have in common

1. Step 1. Android — is used in — Smartphone. The most widespread mobile OS.
2. Step 2. Smartphone — has part — LED. The camera flash.
3. Step 3. LED — is part of — Torch (flashlight). Modern torches use LEDs.
4. Step 4. Torch (flashlight) — has part — Dry cell. Batteries.
5. Step 5. Dry cell — evolved from — Voltaic pile. A convenient form of the galvanic cell.

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