Thursday, July 23, 2009

conducting glass

Click here to see how a piece of glass can become a electrical conductor.

"A small glass tube, held by copper wire, is placed in series with a light bulb. The glass acts as an insulator at room temperature, meaning the current cannot flow between the copper wires. This leaves an open circuit and the light bulb does not light up. Touching a conductor across the copper wires (with a metal screwdriver for instance) does complete the circuit because it allows current to flow.

However, when glass is sufficiently heated by a torch it becomes an ionic conductor. Ionic bonds in the glass are broken, allowing the charge carrying ions to move freely. Thus, when the glass is melted the current can flow, which closes the circuit and lights the bulb.
See the original video on MIT TechTV - http://techtv.mit.edu/file/1104/"
From: MIT youtube channel

Wednesday, July 22, 2009

Dr. Michelle Thaller explains infrared light

Learn more about Infra Red Vision and how does it influence our life.

Tuesday, July 21, 2009

Egg in a Bottle Science Trick

Follow the instructions and learn the classic and fantastic science trick: “Egg in a Bottle"
The hot air inside the bottle cools down reducing the inner pressure, thus the atmospheric pressure will push the egg.

Saturday, July 18, 2009

Paul Hewitt shows how to produce colored shadows

In this video we can see the three primary colors come together and forming white light. Paul Hewitt also shows how to produce colored shadows, that is incredible and fun! Try yourself in home; you’ll need just three lights: red, green and blue.
The TV screens uses the same principle, with this three colors mixed together is possible make any other color, will depends just of intensity of each one.

Sunday, July 12, 2009

Homemade lava lamp using simple materials

Using simple materials is possible make a lava lamp as shown above.
The water is more dense than the vegetable oil, so it sink. When the seltzer tablet is added the gás liberated makes the water float.

Running Pepper: a miracle of surface tension

Here we have another example of science experiments that uses surface tension to works.
Spread peppers in a plate full of water as the video above shows, then put a drop of liquid soap on your finger and put the finger in the middle of the plate to make the peppers run away.
In the post "How many pins is possible to put in a glass full of water" we explain what is surface tension, the soap will reduce the surface tension (the attractive force between the molecules of surface) and the water will run and carry the peppers with it.

Science Experiments: Magic soap bubbles

Baking soda and vinegar are very useful in science experiments, here we have another example in which this materials are used to amaze the people!
Put some vinegar in a aquarium, latter put some baking soda. The result of reaction is sodium acetate and carbon dioxide.
The CO2 is more dense than the air, so a soap bubble will float on it as a boat float on water. The buoyancy force is equal the weight of the bubble, thus we have the equilibrium and the bubble remains on interface CO2 / Air