Electrical conduction and smartphone: what they have in common

1. Step 1. Electrical conduction — is used in — Light switch. Contacts close the circuit.
2. Step 2. Light switch — is part of — Electric bell. A button.
3. Step 3. Electric bell — is part of — Alarm clock. A bell.
4. Step 4. Alarm clock — evolved into — Smartphone. The alarm clock moved into the phone.

Open Evothings