[IR] Plasmas

Plasmas are a lot like gases, but the atoms are different, because they are made up of free electrons and ions of an element such as neon (Ne). You don't find naturally occurring plasmas too often when you walk around. They aren't things that happen regularly on Earth. If you have ever heard of the Northern Lights or ball lightning, you might know that those are types of plasmas.

Aurora. Also Known As the Northern Lights

Ball Lightning

It takes a very special environment to keep plasmas going. They are different and unique from the other states of matter. Plasma is different from a gas, because it is made up of groups of positively and negatively charged particles. In neon gas, the electrons are all bound to the nucleus. In neon plasma, the electrons are free to move around the system.


While natural plasmas aren't found around you that often, man-made plasmas are everywhere. Think about fluorescent light bulbs. They are not like regular light bulbs. Inside the long tube is a gas. Electricity flows through the tube when the light is turned on. The electricity acts as an energy source and charges up the gas. This charging and exciting of the atoms creates glowing plasma inside the bulb. The electricity helps to strip the gas molecules of their electrons.

Fluorescent lights

Another example of plasma is a neon sign. Just like a fluorescent lights, neon signs are glass tubes filled with gas. When the light is turned on, the electricity flows through the tube. The electricity charges the gas and creates plasma inside of the tube. The plasma glows a special color depending on what kind of gas is inside. Inert gases are usually used in signs to create different colors. Noble gases such as helium (He), Neon (Ne), Argon (Ar), and Xenon (Xe) are all used in signs.

You also see plasma when you look at stars.

Sigh.... We won't even be able to see 1/10 of the stars here in Singapore

Stars are big balls of gases at really high temperatures.

How I interpret "Big ball of gas" ;) HAHA.

The high temperatures charge up the atoms and create plasma. Stars are a good example of how the temperature of plasmas can be very different.
Fluorescent lights are cold compared to really hot stars. However, they are still both forms of plasma, even with the different physical characteristics.

[IR] Solid or Liquid

This is an experiment Daryl and I did quite sometime ago, it is about non-newtonian fluids.

Things needed for the experiment.
1. A basin
2. Some water
3. A mixing spoon
4. Corn flour
5. Scissors
6. Measuring cup

Steps
1. Measure about 400 ml of water and pour it into the basin.
2. Open the packet of flour using the scissors.
3. Measure about 400g of corn flour with the measuring cup.
4. Pour the 400g of corn flour into the basin of water.
5. Mix flour with water using your hands.
6. Knead the mixture till it is settled.
7. It should look like melted cheese. Yum... : p
See the resemblance???

Now for the Fun Part!!!

Hit the mixture with force.
You should observe...
It feels hard like a solid, but you can clearly see ripples forming from where you hit the mixture but it does not splash out! You should also observe that it seems impossible to penetrate.

Whereas...
If you gently lay your hand on the mixture, your hand should sink through the mixture. And the mixture would gently flow and fill the spaces in the basin!

Try to...
"Tear" the mixture, you should find that you are able to somewhat "pull" and "rip" the mixture apart like a solid but it gently flows back like a liquid!

"Squeeze" the mixture, you should find that instead of flowing out like a liquid, it suddenly becomes hard and you can feel its shape, like a solid. It should feel like plasticine.

To the molecular level...
The 'Super Starch' is just a liquid with corn flour floating in it, but when you hit it with force, the water molecules are forced into the middle of each grain of flour and it becomes a solid!

In everyday life...
If you run over the wet sand, you should find that it is firm, but, if you stroll along, your feet will sink into the sand.

Why does this mixture have such an interesting property?
Some fluids (liquids & gases) mixtures have two forms.
A liquid can become a solid. This is called "isotropy"

The opposite of isotropy is "thixotropy".
Thixotropy is a liquid mixture becoming "more liquid" (more runny).
An example of thixotropy is when you need to get ketchup out of the bottle, so you had hit the base of the bottle. The act of hitting it at the base makes the ketchup "more liquid" so it can flow out easier.

This is a prezi we also created:

http://www.youtube.com/watch?v=_03fAC0pZ0Q