Book 13, Question 79
Why Does Wet Paper Turn See-Through?
Dry paper scatters light at every air gap between its fibers. Water or oil fills those gaps and bends light less, so more light slips straight through. The wet patch lets more light pass, and it looks see-through.
More fun facts
- Paper is a web of tiny plant fibers.
- You can't see through paper because light passing through gets scattered in many directions.
- Thin materials like eggshells, dry paint and skin block views the same way.
- Scientists are working out formulas for how solids scatter light, hoping to see through them someday.
- Paper towels soak up water between their fibers.
Sources: National Geographic, Scientific American
Questions kids ask
Why can't I see through dry paper?
Light going through it is scattered in many directions.