[paul.fr]

Excellent, Thank you Cameron. Now if the other 6,700 members could post one, just one, what a topic this would be.

what you need

Food colouring
A small jar, or Glass
A larger jar or glass
Aluminium Foil
Rubber Band or Selotape


what you do

Put cold water into the small glass or jar and add 5 drops or so of food coloring. Cover the mouth of the jar with aluminum foil and fasten it in place with a rubber band or tape. Use a pencil point to make a hole at the center of the foil. The hole should be 1/8 inch or so in diameter.
 
Fill a larger jar with warm water. Turn the small jar over and place the foil covered mouth just below the surface of the warm water. Tap on the bottom of the small jar. A ring of colored water will (should) travel downward through the warm water.

If you have a tall vase, then try substituting the larger jar for the vase. This will increase the time before the coloured ring hits the bottom, plus you can make a larger hole in the aluminium foil. Larger holes produce faster moving rings that quickly hit the jar's bottom.
 
Note: A dark coloured water soluble paint can be mixed with the water instead of food coloring.

Pictures to follow at the weekend...

[paul.fr]

Here is one from the magazine Popular Science, attributed to chemist Tryggvi Emilsson

What you need


Microscope slide
Cover slip
Super glue
A sheet of black card
small artist's paint brush
Snow!



What you do


Go outside with some glass microscope slides, cover slips, and superglue (not the gel kind; it should be thin and watery).  Cover the slides and cover slips until they become as cold as the surrounding air. 

Let snow crystals fall onto a cardboard collection board, and scan around with a magnifier to find an attractive specimen.  Carefully pick the crystal up using a small artist's paintbrush and place it on one of the slides.


Place a drop of cold superglue on the crystal, and drop a cover slip on top.  Be careful not to melt or otherwise damage the snow crystal in the process.

Leave the slide outside or in your freezer for a week or two until the glue hardens.

Here is a picture of a snowflake using the above method. As you can see, there are some air bubbles, but practice does make better slides.

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Alternative Method

Another method uses clear acrylic spray paint, which is readily available in hardware stores. The spray is especially effective for replicating windowpane frost and similar ice structures. The (cold) spray must be applied lightly, since the solvent in the spray can dissolve the ice if too much liquid is present.  The best procedure is to pre-coat the glass slide with the plastic film, place snow crystals on it, and then spray the surface again until the surface is moist.   The picture below is from Walter Tape, and was obtained by spraying over a crystal that was placed on a glass slide.

Topic Link:
How Do They Photograph Snowflakes ?

[paul.fr]

Is you area affected by acid rain? Lets find out...

What you need



2 finely chopped red cabbage leaves
distilled water
rainwater
a bowl
2 glass jars
a measuring jug
a sieve



What you do
 
Place the chopped cabbage leaves into the bowl and pour hot distilled water over them, let it stand for an hour. Use the sieve to strain the liquid from the cabbage leaves into a measuring jug. It should be a dark purple colour.
 
Pour 20ml of distilled water into one of the glass jars and 20ml of rainwater into the other, add some of the cabbage juice into the two jars making sure you put the same amount in each. The water will then change colour.
 
 
How does the colour of the water in the two jars compare? You should find that the distilled water stays the same, whereas the rainwater may change colour. It will turn red if the rainwater is acidic; the stronger the acid, the redder the water will become.
 

[paul.fr]

What you need

A clear plastic container (size of shoebox)
red food coloring
ice cubes made with blue food coloring



What you do



Fill the plastic container two thirds full with lukewarm water, add a few drops of red food colouring and let the water sit for a minute or two.

Place a blue ice cube at one end of the plastic container.
Watch... what happens?


Explanation:

This is how a thunderstorm occurs. The blue and cold water sinks while the red and warm water rises. This happens because of convection. The blue water represents the cold air mass and the red water represents the warm, unstable air mass. A thunderstorm is caused by unstable air and convection plays an important part. A body of warm air is forced to rise by an approaching cold front therefore thunderstorm's form.

[paul.fr]

What you need


2 tin cans with the labels removed (soup, baked beans etc...)
rock or table salt
crushed ice (or crushed, regular ice cubes)


What you do


Half fill one of the cans with the crushed ice, and add about 4 tablespoons of salt. Mix it well for about 30 seconds and then let sit.


In the other can put only crushed ice and cool tap water. Fill the can about half way full of ice and then put just enough tap water in the can to cover the ice.


Wait...

What happens?



Explanation:

you should notice frost forming on the outside of the can with the ice and salt mixture. Compare this with the liquid moisture on the outside of the can which contains ice only.


This is how both frost and dew form.

The salt wants to absorb water to make a salt solution. To do that, the salt has to melt the ice into water, melting the ice actually makes the mixture cooler. The salt water mixture inside the can gets below freezing, so the moisture from the air that collects on the outside of the can will freeze. This is why frost forms.
On the other can, dew forms because the mixture of the melting ice and water is just at freezing and the temperature outside the can is warmer causing the dew to form.

You can do this using two glasses, but the effect may not be as noticeable. You may also want to do this using ice cubes, that you have made, that have had food dye added to colour them.
Is the dew or frost that form the colour of the ice cubes, or is it white/clear?

[paul.fr]

What you need

glass jar
plate
hot water
ice cubes


What you do


Pour about two inches of very hot water into the glass jar. Cover the jar with the plate and wait a few minutes.

Now put the ice cubes on the plate.

What happens?


Explanation:


This is how rain is made!
The cold plate causes the moisture in the warm air, which is inside the jar, to condense and form water droplets. This is the same thing that happens in the atmosphere. Warm, moist air rises and meets colder air high in the atmosphere. The water vapor condenses and forms precipitation that falls to the ground.

[DoctorBeaver]

What you need

a nylon comb
a water tap (faucet in the U.S.)

What to do

Adjust the tap so that it produces a small stream of water about 1/16 inch (1.5 millimeters ) in diameter.

Comb your hair. Slowly bring the teeth of the comb near the stream of water, about 3 inches (8 cm) below the tap.

What happens?

Try experimenting with different combs, or with more water flowing.

Explanation

Static electricity. When you comb your hair, a charge builds up in the comb and in your hair (this is the same charge that lets you stick balloons to the wall after rubbing them on clothing). This charge attracts the molecules in the stream of water and causes it to bend towards the comb.

[paul.fr]

Thanks for the contribution, Doc. I hope you have more to come...and similar contributions from other members would also be nice.

Carrying on with the meteorology related experiments.

What you need


small paper bag and a hard surface


What you do


Blow into the paper bag and close tightly to trap the air inside, then smash the bottom of the bag against a hard surface, without letting go of the bag.

What happens?

Explanation
This is how thunder works. Air rushing out of the bag makes a loud noise. The same thing happens with thunder. Air rushes out of clouds after being heated by lightning. This causes the booming sound.

[paul.fr]

What you need


Tall drinking glass, or can with paper removed
Thermometer
Ice cubes
Warm water
Water at room temperature (let it sit for a while)


What you do
 
Put the room temperature water into the glass and add ice, stir with the thermometer until you notice a film of moisture forming on the outside of the glass. Record the water temperature.

Remove the ice and trace your finger on the outside of the glass to make a mark in the moisture. Now raise the temperature of the water slowly, by adding warm water and stirring with the thermometer. Raise the temperature to a point where no moisture forms in the cleared area you marked earlier. When this happens, record the temperature of the water.




Calculate the temperature that is halfway between the two temperatures you recorded, this should be the (or never near to) the dew point temperature of the air.

You can repeat the cooling and warming process several times to see if the results are consistent.

Explanation
This demonstrates 'dew point'.
What is dew point? All air has water vapour in it and warm air holds more than cooler air. When air holds as much water as it can it is said to be saturated. The temperature to which air must be cooled to reach its saturation point is its dew point temperature i.e. 100% humidity. At this point there is a balance between evaporation and condensation. Any cooler and the water vapour will condense as precipitation of some sort. Any warmer and more water will evaporate into the air.

[lyner]

Coupled pendulums.
This is a magical demonstration.
You stretch a piece of string between two supports (as taught as possible Two chairs with people sitting in them will do.
You make two pendulums, using potatoes and string (the victorian parlour trick involves potatoes but anything will do). Get them the same length - the more equal the better effect - and tie them to the horizontal string.
Have one pendulum stationary and start the other. The first pendulum will gradually slow down and the other will build up until the first is stationary. the process will reverse. The rate of changeover depends on the amount of 'coupling' between the two pendulums - the support string twists a little and transfers energy from one to the other.
This has interesting connections with quantum physics and many other resonance phenomena.

[paul.fr]

What a great experiment, Andrew.

what you need

pencil
paper
scissors
a drawing pin
thread, a coat hanger or piece of dowelling
a lamp


what you do


Draw a spiral on the piece of paper and cut it out carefully, it should look like a long snake. Use the drawing pin to poke a small hole in the middle of the spiral and thread the thread through this hole. Tie a knot in the end to hold it together. Attach the other end to the coat hanger or dowelling and hold the spiral above the lamp

What happens?


explanation
As warm air moves upwards from the lamp it pushes against the underside of the spiralnand makes it spin.
This is how wind works. As warm air rises the air pressure underneath it falls and cooler air nearby moves in to take its place. This sideways moving air is wind.

[paul.fr]

what you need

A mirror
clouds


what you do

Place the mirror on a flat area in your garden, or pavement. look at the clouds through the mirror.
What happens?

Explanation
When you Look at the clouds in the sky, you only have other clouds to compare their movement to. If they are all moving in the same direction, they seem to be sitting still (or moving very slowly). If you are looking at their reflection in the mirror, you have the edges of the mirror as a reference point.
This is (roughly) how a Nephoscope works, this is instrument for measuring the altitude, direction, and velocity of movement of clouds.

Why not try looking at the moon through your mirror, does it look to be higher in the sky, or moving quicker?

[JimBob]

 
What you need

A glass
Water
A straw
 
What you do

Suck some water up a straw and then put your thumb over the end that is in your mouth. Now keeping your thumb over the straw take it out of the water. What happens?
Now take your thumb off the end. What happens?

Explanation:
This experiment is all about the forces acting on the liquid. One of these forces is gravity, the force which pulls all objects towards the centre of the Earth. Gravity is pulling the water in the straw down towards the Earth, so why doesn’t the water fall out of the straw when your thumb is on top?

There must be another force, stronger than gravity, pushing upwards on the water. This force comes from air pressure. Air pressure is caused by molecules of air pushing against things. Air pressure is very strong and very important. It affects the weather, and the weight of all the air above us in the atmosphere pushing down is a very large force.

When the straw is just sitting in the glass there is nothing separating the air in the atmosphere from the air in the straw. This means that the air in the atmosphere and the air in the straw are pushing down on the water in the glass with the same force. When you suck on the straw it makes the water move up the straw. If you put your thumb over the end it traps the water in the straw, and your thumb separates the water in the straw from the air pressure of the atmosphere. If you pull the straw out of the water and keep your thumb over the end, the water stays in the straw. This is because there is no air pushing the water down from the top of the straw where your thumb is, but the air in the atmosphere is still coming up the open end at the bottom of the straw and pushing up against the water to keep it in the straw. The force from the air in the atmosphere pushing up is stronger than gravity pulling down! If you remove your thumb from the end of the straw the water will flow back out. This is because without your thumb there, the air is pushing with the same force from both ends of the straw. These two pushes cancel each other out so that gravity can pull the water down to the Earth, just as it was trying to do all along!

[paul.fr]

what you need


two identical glass jars
four cups of cold water
ten ice cubes
one clear plastic bag
a thermometer


What you do


Split the water and the ice cubes evenly between the jars, and wrap one jar in the plastic bag. Leave both jars out in the sun for an hour.
Measure the temperature in each jar

What happens?

Explenation
In reality, sunlight passes through the atmosphere and warms the Earth’s surface. The heat radiating from the surface is trapped by greenhouse gases (the greenhouse effect.)
In this experiment, the plastic bag acts as the layer of greenhouse gases, trapping heat in the jar and causing the water to become warmer in the jar wrapped in the bag.

[paul.fr]

What you need

a large mirror
a dark room
nylon tights/stockings


What you do


Stand in a dark room in front of the mirror and rub the nylon stockings together.
What happens?
Do the same with the wool jumper
What happens?


Explanation
Tiny sparks of static electricity fly back and forth between the two sides of the fabric. When you rub the fabric together electrons build up in one place. When there are lots in the same place, some jump and give off a static charge. This is when you see the spark.

This is how lightning works. On hot and humid days warm, wet air moves upwards very quickly. It forms clouds and the temperature inside the clouds falls. This fast moving air causes an electric charge to build up inside the cloud until the cloud can no longer hold it. The electricity discharges which causes the lightning flash.

[Make it Lady]

If you love all these you are going to die when you see this website.

www.planet-scicast.com

It is full of kitchen science u-tube style films. Search for vacuum cleaner bazooka. Some of them have instructions. Happy experimenting.

Heres one from me:

What you need:

Energy saving light bulb
balloon
Dark room
very woolly jumper

What to do:
Stand in the darkened room. Rub the balloon on the wool jumper and charge it up. bring the balloon close to the light bulb and it should light up just for a moment. With practice and a lot of rubbing you should be able to get the bulb to light up brighter and for a longer period. It looks a little like you have super powers and is a great trick to show the kids whilst reading ghost stories.

Wa Ha Ha Haaaa!

[paul.fr]

Well it's nearly C.S.I. Friday, so how about a few forensic related experiments.

This one is based on Forensic Osteology, the science of bones, and will show how you can determine someones height using their foot!

What you need


Yourself, or a friend
A ruler or tape measure


What you do


With your socks and shoes off, measure the length of your foot, from heel to toe. Next we will compare that measurement to the length of your forearm. If you measure from your elbow to your wrist, you should find that the distance is pretty much the length of your foot.

If you take the length of your foot and multiply it by 7, that should give you a distance very close to your height. If you are under 20 years old, then this may not work. This is because your bones are still growing.

The length of your foot is also the height of your head, from your chin to
the top of your head.

So, from just a few bones a forensic scientist can make some pretty accurate measurements and conclusions.
Why not try it with your friends and family.

[Make it Lady]

Oh Paul I love this one. I once convinced a year 7 pupil that one of the past teachers had really been killed and we had found the bones to examine. The bones were plastic prop.s but this poor kid was convinced it was all real. All these kitchen experiments work so much better if you weave a little story around them. But take care of young gullible children.

[paul.fr]

Posted by: Make it Lady 
Insert Quote
Oh Paul I love this one. I once convinced a year 7 pupil that one of the past teachers had really been killed and we had found the bones to examine. The bones were plastic prop.s but this poor kid was convinced it was all real. All these kitchen experiments work so much better if you weave a little story around them. But take care of young gullible children.

Me too.


What you need

A shoe or foot
A plastic container, about the size of a shallow ice-cream tub.
Plaster of Paris
Mixing spoon
A mixing bowl
Enough moist sand or moist soil to cover the bottom of the container
Rubber gloves


What to do

Put the gloves on and put the sand or soil into the plastic container, and make an imprint of your shoe or foot in the damp sand. If you are not happy with the result, just smooth the sand back over and try again.

Mix up some plaster of Paris until it is nice an creamy, then pour the plaster mixture into the footprint impression. Leave the plaster for about an hour and a half to dry. Once the plaster is dry, remove the cast from the sand. Gently brush off any excess sand.

Why not link this with yesterday's kitchen science. You have a foot cast, can you predict how tall the person was who left the foot print? Is this the print of your suspect, the victim or someone unknown?

[Make it Lady]

What about writing a letter saying that you are being black=mailed by the victim and you think you have found a way to stop it. (In other words MURDER THEM!!!)
If you write with an ink pen you can do chromatography on a sample of ink that came from the letter and different types of ink that came from the suspects pens. They have to find out who's pen wrote the letter.