Water Drops on a Penny – Science Experiment

water drops on a penny science experiment

Have you ever wondered how many drops of water you can put on a penny before the water spills. Okay, what’s your guess? I asked my children the same question today, and their guess was 5 or 6. So, we decided to give it a try and my kids were amazed to see the results. This is a super fun and quick science experiment to do at home, and it only needs come coins and water.


Materials for Water Drops on a Penny

  • Different type of coins – penny, nickel, dime and quarter
  • Eyedropper or Syringe
  • a plate
  • water
  • paper and pencil
water drop on penny material


  • Fill the eyedropper or syringe with water.
  • Rinse a penny and dry it completely.
  • Place the penny on a plate with a flat surface.
  • Guess how many drops you can place on a penny before the water spills. Write your guess on a paper.
  • Attempt to drop water on the penny , one drop at a time, and count the amount of drops
  • Record the results on the piece of paper next to the number you’ve guessed. How did they compare ? Have you been close in your estimated guess?
water drops on penny step by step

The Science behind it

Water molecules are attracted to each other, called cohesion. This attraction creates a bond on the surface called “surface tension.”. When the water reaches the rim of the penny, it begins to bulge over the surface as the molecules cling together. It is due to the surface tension forming a shape that has the least possible surface area. Eventually, gravity overcomes this force as the pile rises and the water spills over the side of the penny.

Further Extension

  1. Try using a nickel, dime or a quarter. What you predict is going to happen ?
  2. What do you think will happen if you used another liquid ( Milk, oil, soapy water etc )

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Here are some more science experiments to try

Happy experimenting !

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