WATERTOWN — This is another installment in the Sci-Tech Museum’s “Homebound Science” program. The Sci-Tech Museum, 154 Stone St., launched the program during the state’s PAUSE order. The science program involves “hands-on” experiments to try with materials found around homes.

Can you scare away a plague of pepper with one finger?

Materials you will need:

  • a bowl
  • ground dry pepper
  • dish detergent
  • Optional: A water glass, paper towel, paper clip

Try this:

1) Fill a bowl with water.

2) Sprinkle pepper evenly over the surface of the water.

3) Put a drop of dish detergent on the tip of your finger.

4) Slowly dip your soapy finger into the bowl.

5. Notice that the pepper runs away from your finger.

What is happening?

The soap on your finger disrupts the surface tension of the water. Surface tension is like a thin elastic skin. It is caused by water molecules clinging to each other because of hydrogen bonds between the molecules.

When the soap broke those hydrogen bonds, the surface “snapped” away from your finger. It was like a balloon pricked by a pin, and the pepper on the surface was carried with it.

Surface tension explains how some animals, such as water striders, can walk and scoot along the surface of a pond.

Optional activity

1) Fill a glass with water — rinse it a few times to make sure there is no soap in the water.

2) Tear a piece of paper towel so that it is larger than the paper clip, but smaller than the opening in the glass.

3) Float the piece of paper towel in the glass, then immediately do step 4 below.

4) Gently lay the paperclip on top of the floating paper towel.

What happened?

When the paper towel sank, the paperclip remained floating on top of the water. Even though steel is denser than water, the paperclip floated because of the water’s surface tension.

Put a drop of dish detergent in the water and notice that the paperclip sinks, once surface tension has been broken.

The Sci-Tech Museum’s gift shop is now open from 10 a.m. to 3 p.m. on Saturdays.

New York state rules prohibit the public operation of its exhibit areas, due to their “hands-on” interactive nature. However, the Science Gift Shop will allow you to purchase science kits, science novelties and unique science-related items meant to intrigue and delight young and old alike for you to use at home. These include gyroscopes, puzzles, mineral specimens, dinosaur models, touchable bubbles, flying things and more.

Johnson Newspapers 7.1

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