Pepper and Water | Science Experiments for kids | Pepper and soap trick
Ever tried a magic trick at home??
This is a magic trick that you can easily master if you understand the concept of surface tension.
• Liquid dish washer gel
• Grounded black pepper
• Take the bowl and fill it with water
• Sprinkle some pepper over the water
• Dip your finger into it and observe. Nothing will happen to the pepper present in the bowl.
• Now, put some liquid dish washer gel on to your finger
• Now slowly dip the finger with the gel into the bowl in the center
• You’ll notice that the pepper which is sprinkled over the water moves away from the finger and rushes back to the outer edge of the bowl.
The pepper floats on the top of water due to surface tension of the water. The surface tension pulls the top of the water together like a skin, so the water bulges up a bit.
Surface tension is the result of the strong attraction between molecules in a liquid. Water has an unusually high surface tension compared with most other liquids because water molecules are very strongly attracted to each other. This strong attraction allows the water to bulge up a bit and makes some insects to skate on its surface.
When the dish washer gel is put into water the surface tension of the water gets ruptured and the bulged part of the water spreads out. So water molecules on the surface are pulled towards the ends of the bowl when the detergent comes in contact with water.
When the surface tension of water breaks, the top most molecules of water spread out and in the process they take the pepper particles away thus making it look as if they are running away from the liquid soap.
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