Light switch and dewar flask: what they have in common

1. Step 1. Light switch — uses — Electrical conduction. Contacts close the circuit.
2. Step 2. Electrical conduction — is used in — Silver. The best conductor.
3. Step 3. Silver — is material for — Mirror. A silver coating.
4. Step 4. Mirror — is part of — Vacuum flask. The silvering reflects heat radiation.
5. Step 5. Vacuum flask — evolved from — Dewar flask. A household Dewar flask.

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