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posted Jan 31, 2015, 5:04 AM by ranmini@charliesresearch.com [ updated Nov 25, 2015, 8:11 PM by Upali Salpadoru ]

1. A cloth can stop water.

For this introductory experiment you need a mug and a piece of cloth to cover the top.. The experiment has to be done outside as you will be spilling a lot of water.
Pour the water into the mug through the piece of cloth as shown in Fig. 1. Once it has got completely filled, pressing the edges of the cloth to the mug, carefully overturn the mug.
Observe what happens.

Fig.1 Completely fill the mug with water.

May be you will have to do it several times. After some time you will be able to keep the mug upside down and yet retain the water inside.

Fig.2 Turn the water filled mug upside down.

We all know that water cannot be stopped by a piece of cotton cloth. Then why wont the water pass out through the piece of cloth?
Like true young scientist it is up to you to think of various reasons and carry out further experiments to investigate the matter. Let us give you a few directions.

Could it be due to the weave and the texture of the cloth?
Is water the only liquid that will behave in this fashion ? What about oil, alcohol and some other solutions such as salt or soap solution?

For a start you may investigate in this line. Just to record your findings let us devise a chart.

Liquid Cloth	Water	Salt water	………….Oil	………………
1. Cotton
2. Woolen
3. ………..

2. Bubbles follow the air.

We do not see air. Yet we feel the air when it blows or when it comes from a fan. How do we check the movement of an invisible substance?

The experimental method is to use tracers. A tracer is a substance that can be seen or detected by a sensor. When the branches sway and the leaves fly, we conclude that the air is moving.

Fig.1. Bubbles follow the air movements.

Our experiment is to find out how the air moves around a hot body such as a candle flame or an electric iron.

Take an empty card board box. Open the lid and place a board of a non burning material at the bottom. Cut a window on one side and paste a cellophane paper so that you can see inside. Keep a hot electric iron or a burning candle on the non combustible surface. [If you cannot find a non combustible substance you may add a layer of sand.]
Close the lid keeping the end of the power cord out. Make two openings at the top As an additional measure, fix two pieces of thick paper rolled up as cylinders. (not shown in the diagram)

Switch on the iron. If it is a lamp or a candle, light it carefully. Close the lid and place the two chimneys A and B.    Blow soap bubbles near the box and see what happens.

You may even use smoke from a jossstick instead of soap bubbles.

Vocabulary
Movement of a gas or a liquid carrying heat energy is called a convection current.

WARNING
If you are using an oil lamp or a candle, you must have some water ready to extinguish the fire if the box catches fire.

Explanation

Air particles touching the hot object gets heated. This increases the volume of air making it lighter. or less dense. So the hot air goes up. As this lowers the pressure new air rushes in.

3. Water moving up-Capillary Force.

"Hills and vales go rolling round

Water glides and cascade down"

Fig. 1. A water Falls in New Zealand South Island.

“Believe it or not; water can run up at times” “Let’s take the garden hose and open the tap”. (Water gushed up forming a fountain.)	“It’s impossible”. “You are trying to deceive. The water comes to the pipe line from an overhead tank.”
“What about the siphon that we use to remove water from an aquarium"	“Even then the fish tank has to be at a higher level”
“OK! Let’s do an experiment”

.Experiment 1.

What you need.

Glass or plastic tubes of different size. (like drinking straws)
A trough or a cup of water.
Food colour or some dye.

Take some water into a cup. Colour the water with a dye so that you can see the levels clearly.

Insert a few plastic or glass tubes of different diameter.

Can you believe; this is what happened.

Fig.2 Water rises up in thin tubes.

Fig.3 Cohesive and adhesive forces.

You may like to know why water rises in thin tubes. All substances are made of particles called molecules. Every molecule gets attracted to every other molecule. This is known as ‘inter molecular attraction’.

There are two kinds of these attractions. For example in water there will be an attractive force between two water molecules. This is called ‘cohesion’ . Water molecules will also be attracted to the container, which may be glass. This is called ‘adhesion. In the diagram you will notice that the layers 1 and 2 are closer than layers 2 and 3. The reason for this is that the top layer is not pulled up by the liquid molecules. This is what causes ‘surface tension’.

When the adhesive force is stronger than cohesive force the water rises,

Applications and Projects

Experiment 2

When one end of a piece of cotton cloth is dipped in water or oil as in certain lamps it will absorb the liquid. This is due to capillary force. Set up these apparatus using plastic bottles and watch how the water drips in the empty beaker. Find out the following.

Fig.4 A capillary siphon with a piece of cloth.

You can also try this using muddy water in the reservoir. How is the water at the other end?

Fir

Capillary action is mainly responsible for ascending of water in trees. The xylem vessels are so thin that the water absorbed by the roots are pulled upwards.

Experiment 3.

Another project is to find out how the water rises in soil. You can take different soil into tubes of an diameter and find out up to what height the water rises

in different types such as sand, clay etc.

One advantage of tilling the top soil for agriculture is to stop the water coming up to the surface for evaporation.

4. Easy circuits.

Here's a way to build electrical circuits without soldering. An idea burrowed from The University of St Thomas.

What need is flour, oil, salt and sugar apart from torch cells, wires and transistors or bulbs.

Making Insulating Dough.	Making Conductive Dough
1 1/2 cup.................. Flour 1/2 cup .....................Sugar 3 Tbsp. .....................Vegetable Oil 1 tsp. Granulated Alum (optional)(Thishelps preserve the dough.) 1/2 cup ....................Water ( Rain water or distilled water is preferable)	1 cup ............................Tap Water 1 1/2 cups................... Flour 1/4 cup........................ Salt 3 Tbsp. ........................Cream of Tartar 1 Tbsp. ........................Vegetable Oil Food Coloring (optional)

Mix the substances in a pan and cook it on a hot plate stirring it until the mixture boils. Cut off the heat and stir until it becomes a paste that you can handle. When cool knead it using a bit of flour if necessary to reduce the stickyness,

Now you can use this to connect the ends of the wires in any type of a circuit upto about 6 volts,

Good luck.

5. Finding the favourite Flavour

When a kid says a particular popsicle is ‘yummy’; what does he mean by that? Well Rakitha designed an experiment to find this out. He had four coloured drinks topped in identical glasses. Then he added straws into them and summoned some of his friends and relations to taste them. His method, entering and analysis of the results were as follows;

Fig. 1. Finding the favorite.

Method:

When a straw is dipped into a drink some of the juice enters the tube. If you just lift it
juice flows out. If you keep your mouth to it your saliva will contaminate the drink. If you
close the open end of the tube with your finger and lift the straw some juice can be lifted
out. This portion can dropped to your mouth without contaminating either the tube or the
drink. This method can also make sure you always take the same quantity if you maintain the
height of the column constant.

Once you taste a specimen some part of it can remain and contaminate the next sample. This can be avoided if you drink some water in between tasting. The participants were asked only to select his or her tastiest sample.

Recording

The results were recorded in a chart.

Participent	Green	Blue	Yellow	Red	SAME
Ama
Mehara
Kevin
Nuran

Fig.2 How they selected their favourite taste.

Analysis ( These are not based on the above chart)

Green
Blue
Yellow
Red
Same

Fig.3 Bar graph analyzing the results.

According to the results red coloured sample seems to be the most popular. But is it?
The key is that it was the same, identical drink that was coloured using food colours
having no taste at al

5. Brilliant halo from a CD.

This time Ali and Nelly achieved a really cool way to get brilliant colours. Anyone who has handled a CD will know that it can gleam in vivid colours when viewed at an angle. They argued that if a beam of parallel light, such as sun light is flashed on to a cd. It must throw out different colours. Their idea is depicted by this diagram.

Fig.1. Getting the colours from a CD.

In the 17th century there were no cd s. Sir Isaac Newton obtained the spectrum by passing the light through a prism. He distinguished seven colours.

Can this really work? Nelly’s friend Mehara actually carried out this experiment. First time she failed. There was too much light on the wall. When she tried on a white shady part of the wall about a meter away from Cd, she got the best results.

Now you may wonder what happened to Indigo which is the second colour in the former term VIBGYOR. These are the first letters taken in the reverse order. As an explanation for the omission of indigo let us quote the internet. “In modern usage,

Here the CD cannot be seen clearly. The white part on the carpet is the area lit by the sunlight. Only a part of the halo is seen here, but it is possible to get the complete circle. The order of colours can be remembered as ….

ROY Grows Blue Violets

( indigo is not usually distinguished as a separate colour in the visible spectrum; ”)

More activities There are many more variations a young scientist may try out.

Here is one suggestions\:-.

The path of light rays are not visible. It can be made visible by smoke. Try to get smoke between the CD and the wall.
Find more about Sir Isaac Newton.

Refer:- Dispersion of light under Nature of light.

6. Electrical conduction in materials.

You need 4 Paper clips, 9v battery. a torch bulb with a holder or an LED & some wires.
Diagram

Clean the ends of the wires by removing the insulation, Attach them as in the circuit diagram using paper clips or by some other way. If the detector is an LED, it will light up only for a current in one direction. Before attaching any object material the ends of the blue and the red wires must be connected to test the circuit. If the LED or the bulb lights it’s OK.

Then attach a strip of the material you wish to test to the circuit as shown.
Copy this chart into your note book and enter the results. Only a few examples are given here You can test any number of materials.

Item used	The guess of your friend	Your guess	Conductor / Semi conductor / Insulator.
A strip of aluminium foil.
A strip of plastic.
A rubber band
A piece of cloth dipped in salt

Test a few more materials available in your home.

Click:- Alan Mc Diarmid of NZ

2 b. Measuring Friendship.

Take the hand of your friend just as you shake hands. With your free hand hold the paper clip of the red wire. Ask your friend to grip the other clip. Make sure you make firm grips. If he is a good friend, the LED will light.

7. Measuring Rainfall

It was raining cats and dogs. Ali and Nelly saw rain water getting collected into a large barrel. Unlike the water that falls on the ground, which either gets soaked up or flows down the slope into streams, water in a barrel will stay. So they got an idea.

Fig.1 All the rain above the barrel gets inside.

Their dialogue was as follows;
Ali :- There ! We can measure the water in the barrel”.
Nelly:- “I cannot remember the formula to find the volume of water in a cylinder”
Ali:- “ No need. We can measure the height.”
Nelly:- “The height of rain? “
Ali:- “No. silly girl. After the rain we can dip a stick into the barrel and find out the height of water collected in it”.
Nelly:- “ How brainy you are? Now I remember , rain fall is always given in millimeters.”

You don’t need a barrel for this. We can do it in a very small scale. Here are the steps for you to measure the rainfall every day; so that you may know the usual dry months and wet months of the year.

Step 1

Get an empty plastic mega bottle. Draw a ring round the neck with a marker. Get a friend to hold the bottle tightly if you cannot clamp it. Take a bread knife and carefully cut an insertion. [Beware- Knife might slip on plastic.] Then with a pair of scissors you can easily separate the top part of the bottle. This is shown in Fig.2.

Fig. 2 Making an insertion with a bread knife.

Step 2

The bottom of these bottles is usually curved. How can that be made flat? One way is to pour something like cement. Mix one part of cement with about two parts of soil make it into a paste with water and add it until the curved bottom becomes flat. If cement is not available you may even use some other substance like clay. If you use a substance like sand you must add water to cover up the pores.

Step 3
Unscrew the cap and make a few holes in it with a nail. Then tighten the cap to the top part, invert it and slide it into the bottle as a funnel. Then paste a strip of graph paper to measure the height of water.

Fig.3 Bottle Rain gauge.

Keeping Records.

It is interesting to keep a record of rain fall. This can be done very neatly using a square ruled exercise book or better a graph book. If the rain fall was 10mm , you can colour up to the violet line. On the second day it was 20.5 mm. Third day no rain. 4th day 2mm.only. This is how you should keep your records

8 . Making a sprayer.

If you blow air , will there be a high pressure or a low pressure in the stream?

"It ought to be Uigh"

Experiment

Take two long strips of paper . Let them hang from your hands as shown here. Then blow air between the two strips. What do you think would happen

If you use a blower the effect would be more impressive.

Big. Blow air between the two strips.

It was Daniel Bernouli, a brilliant mathematician who solved this in the 18th Century. So the pressure phenomenon that result from fluid flow is described as Bernouli Effect. (It is worthwhile reading his life history in the Biography category.)

Bernouli Principle

Fig. An application of the Bernouli Principle.

Keep a thin plastic tube dipped in a cup of water. The water may be coloured so that you could see the level clearly. Take a barrel from a ball point pen and cut it into two. Fix the part with the pointed end to a balloon. Tie it up with a string so that air may not leak. Keep the other part verticlly with one end dipped in water. Now blow the balloon through the jet tube .. Place the jet in line with the opening of the tube and release the air .
Water will get drawn up. Do you know why?
If you wish to know about Bernauli brothrs and their father go to Bernauli Family.

9. Magic string

Here is an interesting experiment that can make you a magician.. There is a ring or some light object hanging from a loop of a cotton thread. You can utter a manthra and burn one strand, the ring will not fall. If you burn the other strand, without the manthra, the ring falls down','Method.

Ask for a cotton thread about a meter long from your mother. Make a strong salt solution into a saucer and immerse about half of the thread in the solution. That part of the thread will absorb the salt. Keep it for about ten minutes and then dry the thread by keeping it in the sun.. After drying there will be no visible difference between the two ends. Then borrow a gold ring and pass the thread through that and tie the two ends making a reef knot. Place a metal ruler or a rod on a table and keep it steady by a weight such as a book. Insert the top end of the loop into the rod and let the ring hang as shown in the picture. It is important to keep the salted strand and the other part separate. It is easy to identify the salted end if you let the knot come to that side.

Ask your friends what would happen if you burn the string. Many will say, “ The thread will break and the ring will come down”. Get a candle flame and burn the salted strand uttering some sort of manthra just to deceive your friends.. To everybody’s great surprise the thread will not break. Then ask the same question again with regard to the other thread.. Then burn the other end without the manthra. The ring will fall.

Why it happened?

Cotton which is a compound when burnt a black substance Carbon is formed. ( This is the same as charcoal) These particles are not linked together tightly. In the case of salted threads salt which remains without burning can bind the carbon particles together.

Projects for the young research scientists.

1. Use cotton threads of different thickness and find out what weight they can hold.
2. Use different solutions and find out how many paper clips are necessary to break the thread.
Examples of solutions:- sugar, soap , lime etc.

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