Recent content by c.s.

Interesting! I tried to crack the bead in half and found that the color change started from the surface (where the light from the UV torch shone on) and then to the interior. However, I forgot to take a picture of it. Will do it when I return to my office.

HEV means high energy visible (HEV) light?

Do you mean if the film is blue, it absorbs yellow/ orange area light and allows blue light to pass through? And if the blue film absorbs less UV light, does that mean it allows more UV light to pass through so the beads turn darker purple?

Thanks everyone for the questions and ideas. I've taken a few photos to help you guys understand the experiment. Original colors of the beads: http://dc182.4shared.com/img/336849520/50116542/01022010091.jpg Covered by cellophane paper of different colors...

Thanks Andy, for your reply and questions. Since the beads are not sensitive to visible light (as stated on the package), the color change should be caused by UV. It seems that the cellophane of different colors allow different amount of UV to pass through. However, UV is not part of the...

I've got some beads that will change color under sunlight. The stronger the intensity of sunlight, the darker (purple) the beads will turn. If the beads are put back indoor, they will resume their original color (white) after a while. The beads will also change color if they're under the light...

Oh by the way, Stonebridge, I guess we can't compare the experiments carried out by students are the elementary level with those carried out by scientists. You know, many of the schools don't even have money for a decibel meter. It's just very important for the teachers to remind students to try...

Thank you so much everyone for the replies. All of you helped me to understand this experiment a lot more. Somehow, I think this experiment is pretty difficult for 2nd an 3rd grade students. It's not only because of the concept of sound is difficult, it is also because the pitch and the...

Thank you so much for the explanation, Danger. And I'm really sorry about the colour of the text. But I have a question, does the volume of the air space within the bottle affect the frequency (the pitch) or the amplitude (the loudness)?

I recently read an experiment from a science book for elementary school students. Basically, it asks students to compare the loudness of sound produced by shaking the small plastic bottles containing different amount of red beans. There're altogether 4 plastic bottles, filled with red beans to...