Friday, September 17, 2010


 Pringles Pinhole
What Do I Need?
45 Minutes
  • empty Pringles® chip can
  • marker
  • ruler
  • X-Acto knife or utility knife (ask a grown-up to help you cut)
  • thumbtack or pushpin
  • masking tape
  • aluminum foil
  • scissors (if you want)
  • bright sunny day
 Kid looking through can
What Do I Do?
1 Take the plastic lid off the Pringles® can and wipe out the inside. (Save the lid!)

2 Draw a line with the marker all the way around the can, about 2 inches up from the bottom. Have a grown-up cut along that line so the tube is in two pieces.

Marking the can

3 The shorter bottom piece has a metal end. With the thumbtack, make a hole in the center of the metal.

 Putting the can together

4 We're going to use the plastic lid as a screen. If your lid is clear, you may need to apply a piece of wax paper, white tissue paper, or vellum to the lid to act as a translucent screen. Put the plastic lid onto the shorter piece. Put the longer piece back on top. Tape all the pieces together.

5 To keep light out of the tube, use a piece of aluminum foil that's about 1 foot long. Tape one end of the foil to the tube. Wrap the foil all the way around the tube twice, then tape the loose edge of the foil closed. If you have extra foil at the top, just tuck it neatly inside the tube.

Covering the can

6 Go outside on a sunny day. Close one eye and hold the tube up to your other eye. You want the inside of the tube to be as dark as possible-so cup your hands around the opening of the tube if you need to. Look around your yard through the tube. The lid makes a screen that shows you upside-down color pictures!
7Hold your hand below the tube and move it very slowly upward. Your hand is moving up, but you'll see its shadow move down the screen!  Kid looking through can

What's Going On?
How does a hole in the bottom of a Pringles® can make a picture of the world?
The hole doesn't make the picture. The image of the world is always there. All the hole does is make it possible for you to see it.
Suppose you point your Pringles® Pinhole at a brightly lit bouquet of flowers. Light reflects off the red rose, the blue iris, the white daisy, and the green leaves. If you hold a piece of white paper near the bouquet, some of that reflected light will shine on the paper-but it won't look like anything. That's because light bouncing off the red rose ends up overlapping with light bouncing off the blue iris, the white daisy, and the green leaves. There are many images of the bouquet on the paper-but they overlap with one another, and the colors all blend together, making a jumble of light.
The hole isolates a small part of the light, sorting a single image from the jumble. Only a few of the light rays reflecting off each point on the rose are traveling in a direction that will let them pass through the hole. The same is true for light bouncing off all the other flowers in the bouquet. On the other side of the hole, these light rays reveal an image of the bouquet.

 Wow! I Didn't Know That!
You've made a camera! This kind of camera is called a camera obscura-which is Latin for "dark chamber." The first camera obscuras were small rooms that were completely dark except for a tiny hole in a wall that let in a dot of sunlight. People in the room saw an image of the trees and sky on the wall opposite the hole-and were amazed when the image disappeared at sunset!
The Home Scientists in the Graff family improved their Pringles® Pinhole by using a foam soda can holder as an eyepiece. It made the inside of the tube dark, and was easier to use for people who wear glasses.


Tuesday, September 14, 2010

Raya di rumah guru dispilin...

Syawal kali ini di meriahkan lagi oleh kehadiran pelajar SMKBK. Sesunguhnya cikgu mengucapkan terimakasih dan berbesar hati atas kehadiran kalian. Sesungguhnya cikgu tidak pernah sedikitpun menyimpan apa-apa perasaan dendam atau marah. Cikgu hanya menjalankan tugas cikgu dengan tulus dan ikhlas. Prinsip cikgu, yang salah kena betulkan kerana kita memang kena berpesan-pesan dengan kebenaran.  Salam aidil fitri dan maaf zahir batin..

Sunday, September 12, 2010


Water Rocket

Water rocket

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Water rocket launch
A water rocket is a type of model rocket using water as its reaction mass. The pressure vessel—the engine of the rocket—is usually a used plastic soft drink bottle. The water is forced out by a pressurized gas, typically compressed air.
The term "aquajet" has been used in parts of Europe in place of the more common "water rocket" and in some places they are also referred to as "bottle rockets" (which can be confusing as this term refers to a firework in other places).