Liquid nitrogen and smart meter: what they have in common

1. Step 1. Liquid nitrogen — is used in — Dewar flask. Storage.
2. Step 2. Dewar flask — uses — Vacuum. A vacuum.
3. Step 3. Vacuum — is used in — Magnetron. It works in a vacuum.
4. Step 4. Magnetron — has part — Permanent magnet. A magnet makes the electrons spiral.
5. Step 5. Permanent magnet — is part of — Electricity meter. A braking magnet.
6. Step 6. Electricity meter — evolved into — Smart meter. A digital meter.

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