- Dish washing liquid
- Plate Or Bowl
- Pour water into a plate.
- shake some pepper into the water.
- Dip the finger into the plate. Nothing much happens.
- Put a drop of dish washing liquid on finger and dip it into the plate the pepper will rush to the outer edges of the plate.
Add detergent to water the surface tension of water is lowered. So the water wants to spread out. So the water is carried the pepper to the outer edge of the plate.