[paul.fr]

KITCHEN SCIENCE - Why sodium street lights make things look orange
on the 18th of february 2007.

For those of you who did this kitchen science experiment; Try repeating the experiment with a cd or dvd, try it under all colours of street lights and even neon sign displays. oh, go on...

Paul

[daveshorts]

That is a really nice idea.

[paul.fr]

Thanks, Dave.

I should have mentioned that it should be a blank disc, and not one that has data on it.

Paul

[daveshorts]

Does this make a significant difference?

[paul.fr]

I have only tried it with a blank disc, and my thinking is that the blank CD or DVD is smooth as opposed to the one that has data written on it which has all of those peeks and troths.

Then again you could use a blank and a non-blank disc and compare the two results

Paul

[paul.fr]

I have now tried it with both blank and written discs, and there is no difference.

Paul

[Karen W.]

I just nooked a unwritten music cd and set timer for 5 seconds and watched a brillant teal blue green sparkle show which was quite lovely. It would have been nice if the sparks were higher then 1 inch up off the CD, but they were lovely anyway. It left a circular pattern on me CD that resembled a brick wall on both sides. almost reminds me of old antique paint that is crackled ! What causes this to spark like that is there some small amount of metal on a CD or what?

[paul.fr]

karen,

whilst you wait for an answer, why not post it as an experiment here: http://www.thenakedscientists.com/forum/index.php?topic=6730.0

[Karen W.]

Something else I noticed, It smelled slightly not during but when I opened the door for about 15 minutes or so. Just a slight smell, not strong! Is that odor safe or can that be something you shouldn't breath?

[paul.fr]

I just nooked a unwritten music cd and set timer for 5 seconds and watched a brillant teal blue green sparkle show which was quite lovely. It would have been nice if the sparks were higher then 1 inch up off the CD, but they were lovely anyway. It left a circular pattern on me CD that resembled a brick wall on both sides. almost reminds me of old antique paint that is crackled ! What causes this to spark like that is there some small amount of metal on a CD or what?

Karen, was in an regular cd or a re-writable one? you could try doing it again with another disc of the same type and see if the pattern burned into the disc is the same.

as for the smell when you opened the door. best not to breath too much of it in, just leave the microwave to vent for 15 minutes afterward.

[daveshorts]

Either type of disk has a thin layer of aluminium in the middle of it. In a conventional CD the data is stored by making pits in this which alter how the light reflects, and in a rewritable one it is done with a layer of a dye above this.

When you put a CD in the microwave, the microwaves induce very large currents to flow in this aluminium layer, the currents are so high that it starts to heat up and change shape. This tends to make it crack up, when a crack forms suddenly the currents often will jump the gap through the insulator/air as a spark. Once a crack forms the currents will tend to go in different routes heating up different bits of aluminium and causing them to crack. This goes on until the pieces of aluminium are too small to build up large currents so it stops cracking, and just gets hot.

[Karen W.]

Pa

I just nooked a unwritten music cd and set timer for 5 seconds and watched a brillant teal blue green sparkle show which was quite lovely. It would have been nice if the sparks were higher then 1 inch up off the CD, but they were lovely anyway. It left a circular pattern on me CD that resembled a brick wall on both sides. almost reminds me of old antique paint that is crackled ! What causes this to spark like that is there some small amount of metal on a CD or what?

Karen, was in an regular cd or a re-writable one? you could try doing it again with another disc of the same type and see if the pattern burned into the disc is the same.

as for the smell when you opened the door. best not to breath too much of it in, just leave the microwave to vent for 15 minutes afterward.

Paul it was a regular Staples brand CD-R recordable. 80 minutes 700 MB, 52X, 1x - 52x compatable! I did two of them to see if the pattern was the same. Yes indeed it was ! Same pattern both cds, back and front, They will make charming coasters for a wedding...centerpeice LOL maybe a small Goldyfish bowl on top!! LOL!

Yes, the smell was mild but stunk and I opened my kitchen window and let it air out! wasn't too bad!

[paul.fr]

nice, i asked the question purely so you could repeat the experiment and see what you got the second time. You would have got a similar pattern. i find it good to do things twice and compare the results, plus you now have two coasters and not one all alone and sad.

[Karen W.]

Yes I do belive that is the pattern on my pair of new coasters! LOL Yours looks more colorful then mine!

[paul.fr]

Dave, have you not thought of "doing a chris" and publishing you own book?
kitchen science, by dave ansall (is that the right spelling)

think of all the lovely shoes rosy could buy with the money!

[daveshorts]

We will see - although if it made enough money for Rosy to buy all the shoes she wants to buy, it would only have to sell about 2 copies - all the shoes she needs would probably need a couple of hundred.

[paul.fr]

 []

[daveshorts]

( this is in response that all the shoes she does own are falling apart, and we have to keep going to her parents house in order to root out others which still have soles attached )

[rosy]

It's not true! None of the shoes I own are falling apart... I threw away the ones that were. Well, most of them, anyway...

[paul.fr]

Why do girls think shoes are falling apart, when they have only been worn twice? Looks like you may have to write a second book, Dave.