Band theory and gutenberg printing press: what they have in common

1. Step 1. Band theory — is used in — Semiconductor. Band theory explains the properties of semiconductors.
2. Step 2. Semiconductor — includes — Gallium arsenide. A semiconductor.
3. Step 3. Gallium arsenide — is material for — Laser diode. Laser diodes.
4. Step 4. Laser diode — is part of — Laser printer. A laser draws the image on the drum.
5. Step 5. Laser printer — is a kind of — Printer. A printer.
6. Step 6. Printer — works like — Gutenberg printing press. A printer is a personal printing press: it transfers an image onto paper.

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