Experiment #8: Soap Bubbles

Soap bubbles are interesting for everyone. My 18 months old girl loves it, my 4.5 years old boy loves and I love it too. Yesterday my mother-in-law was busy cooking an awesome Tamil Nadu meal of Mutton Biryani, Mutton Curry, and Rasam. On Saturday we went to Hidden Villa, Los Altos. I have shared details in this post.

Since I had the time, I decided to spent it with my kids. We were snacking on pistachios and saved its shells to make art work. We will reveal it next week as he needs to paint the dried shell. We made a greeting card with it.

 

After that we did an experiment with soap bubbles. Water excites my son. He loves to play with it all the time. Yesterday we used water, soap and straw to make bubble mountains. When air is blown through straw into a container, cascades of bubbles are created which rises high and falls over the rim.

 

 

 

What is the science behind bubble?
In our case, I had the opportunity to talk about shapes and light. For older kids, we can talk about surface tension, geometry and chemistry. For pre-schoolers like my son, this experiment will help them investigate, discover and explore the world of magical bubbles.

 

What is a bubble?

 

A bubble is nothing but air wrapped in soap film. It is made of soap molecules. The bubbles always take a sphere shape because that has the smallest surface area for the amount of volume. When you blow, bubbles stretch and takes all crazy shape. Once its sealed and release into the air, the tension in the bubble skin shrinks to the smaller shape for the volume of air that got trapped inside it.

 

What you need?

• 8oz plastic tumbler
• Few drops of dishwashing soap
• Straw
• Happy kid who loves bubbles
• Kitchen Sink or Bathtub or Patio or Backyard

How to do it?

1. Add water to fill half of the tumbler. Add few drops of dishwashing liquid. Stir with the straw.
2. Ask the child to blow air through the starw so bubbles start emerging on the surface. Let the child to make a tall mountain.
3. Repeat and let the child have fun

As he made the bubbles, I asked him the following questions.

1. What is the shape of the bubbles?
2. What colors do you see?
3. How high can he make the bubble fountain?

 

My 18 month old daughter stood next to him and kept popping the bubbles. She enjoyed it too.

 

 

 

Have you noticed that bubbles pop even without being touched or poked?

That is because they pop when the water between the soap film surface evaporates.

 

We did the experiment in the kitchen sink. There is a window right above the sink. The sun rays fell on the bubble and gave a prism effect. Katli was excited to see rainbow colors in the bubbles. A buble gets it color from light waves reflecting between the soap film. Bubbles can also reflect whats around them like the faces around them.

 

In the picture, you can see that the bubbles got the hexagon shape. It looked like beehive. When bubbles are about the same size, they form perfect hexagons. My son has always seen only bubbles that are round and so this was something new for him.

 

 

Experiment #3: How to create tornado in a bottle?

What is a tornado?

Wikipedia defines tornado as "A tornado is a violently rotating column of air that is in contact with both the surface of the earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. They are often referred to as twisters or cyclones,although the word cyclone is used in meteorology, in a wider sense, to name any closed low pressure circulation."

My son and I decided to create a tornado in a bottle. We can replicate the effect on a smaller scale with simple items like dish washing liquid, glitters, water and bottle. 

Aim: To create tornado in a bottle using simple kitchen items

Things needed:

1. 1 glass bottle
2. Water to fill it 3/4 th or less
3. Glitters ( I bought this at Walmart)
4. Dish washing liquid 
5. Funnel

Method:

1. Set up the working area. I used a plastic tray to catch the spills.
2. Fill the bottle with water (3/4th or less)
3. Add few drops of dish washing liquid
4. Place the funnel in the neck of the bottle, ask the kid to sprinkle lots of glitter into it (More glitter in the water, more visible will be our tornado in a bottle)
5. Tightly screw the cap to the bottle. Check well so there is no leaks
6. Turn the bottle upside down and hold it by the neck. Spin the bottle in circular motion for some time, about 10-20 seconds, stop and look at the mini tornado forming in the water. 
7. We had to try it few more times to get it right. So keep swirling it and sing to your child for each round you make:

"Round and round the garden

Like a teddy bear

One step, two step

Tickle under there"

What actually happens?

When you spin the bottle in circular motion, it creates a water vortex. You will see water spinning around the center of the bottle. This is due to centripetal force. It is an inward force which directs the object (in this case water) towards the center of its circular path.  This effect looks like a mini tornado.