Why do DVDs scatter blue light and CDs scatter white light?

  • Thread starter daniel_i_l
  • Start date
In summary, the difference in color between a blue DVD and a white CD is not due to density, but rather the materials used in their production. The smaller particles on a DVD's surface cause it to scatter blue light, while the larger particles on a CD's surface scatter white light. The composition of clouds and the clear-blue sky also play a role in their color, with clouds being made of larger particles and the sky being made of smaller particles.
  • #1
daniel_i_l
Gold Member
868
0
In the sky the less dense parts of the sky scatter blue light and the denser clouds scatter white light. So why does a CD scatter relativly white light and the denser DVD blue light?
 
Physics news on Phys.org
  • #2
What do you mean? Why is a blue DVD blue? It can be blue because a blue azo dye is present on the data layer. The data layer can also be metallic which might look as if it is scattering relatively white light.
 
  • #3
The claud and sky scattering has little to do with density.
 
  • #4
Some dvds are "denser" than others? What does that even mean? There are several different processes by which DVDs and cds are made, using different materials that have different colors. "density" has nothing to do with it.

Clouds are not the same composition as clear-blue sky so it isn't correct just to say that a cloud is "denser". The mechanisms to cause the color have nothing at all to do with others. Atomized liquid water is essentially opaque white.
 
  • #5
Thanks for the replys.
russ_watters said:
Some dvds are "denser" than others? What does that even mean? There are several different processes by which DVDs and cds are made, using different materials that have different colors. "density" has nothing to do with it.

Clouds are not the same composition as clear-blue sky so it isn't correct just to say that a cloud is "denser". The mechanisms to cause the color have nothing at all to do with others. Atomized liquid water is essentially opaque white.
I think I should explain myself better:
First of all, the reason that clouds are white because it is made out of bigger particles than the particles in the "clear-blue sky" (this is what i meant by denser)
http://acept.asu.edu/PiN/rdg/sky/sky.shtml
http://math.ucr.edu/home/baez/physics/General/BlueSky/blue_sky.html
http://hyperphysics.phy-astr.gsu.edu/hbase/atmos/blusky.html

CDs and DVDs store memory by small indentations on the surface. The ones with more memory (DVD) have more indentations that are closer together and smaller.

But maybe the key here is the smaller, not the closer together. Just like the smaller particles of the clear-blue sky scatter shorter wavelengths (blue) and the bigger particles of the clouds all the wavelengths (white), the DVD with smaller holes scatters blue light and the bigger CD holes white light? Or is the color difference related only to difference in materials?
 
Last edited by a moderator:

1. What causes white clouds to form?

White clouds are formed when water vapor in the atmosphere condenses into tiny water droplets or ice crystals. These droplets or crystals are so small and spread out that they reflect all colors of light equally, giving the appearance of white clouds.

2. Why are DVD discs typically blue in color?

DVD discs are typically blue in color because they use a blue laser to read and write data. The shorter wavelength of blue light allows for more precise and compact data storage compared to the longer-wavelength red laser used in CDs.

3. How do DVDs store and play back video content?

DVDs use a digital format to store and play back video content. The video is encoded into digital data, which is then stored as microscopic pits on the surface of the disc. When the disc is played back, the laser reads these pits and converts the data into video and audio signals.

4. Do white clouds or blue DVDs have any practical applications in science?

Yes, both white clouds and blue DVDs have important scientific applications. White clouds play a crucial role in the Earth's water cycle and climate, while DVDs have been essential in the development of digital storage and media technologies.

5. Can DVDs be damaged by exposure to white clouds or other weather elements?

Yes, DVDs can be damaged by exposure to extreme weather elements such as extreme heat, humidity, or direct sunlight. It is recommended to store DVDs in a cool, dry place and handle them carefully to avoid scratches or damage to the disc's surface.

Similar threads

B A silly question about why the sky is blue
    • Other Physics Topics
Replies
4
Views
11K
Why is the Sky Blue? Understanding Rayleigh Scattering and Atmospheric Particles
    • Other Physics Topics
Replies
23
Views
4K
I Rayleigh scattering -- What is the true reason for the color of the sky?
    • Electromagnetism
2
Replies
57
Views
3K
Why do sunsets appear different colors than the sky?
    • Other Physics Topics
Replies
7
Views
2K
B Why do oceans look blue from orbit?
    • Other Physics Topics
Replies
10
Views
7K
Why are Clouds White? Raman Effect & Rayleigh Scattering
    • Other Physics Topics
Replies
5
Views
2K
B Scattering of light inside a room
    • Optics
Replies
22
Views
1K
Why don't nearby atmosphere look blue.
    • Other Physics Topics
2
Replies
36
Views
4K
I Red-orange skies and wildfires
    • Classical Physics
Replies
1
Views
752
I Thomson Scattering when low-intensity light meets an orbital electron
    • High Energy, Nuclear, Particle Physics
Replies
5
Views
993

Hot Threads

Recent Insights

Back
Top