Calculating Bit-Density of a CD using AFM Images

  • Thread starter Thread starter SarahBoberra
  • Start date Start date
  • Tags Tags
    Calculation
AI Thread Summary
AFM images of a CD revealed 224 bits in a 900µm² area, prompting a calculation of the bit-density for the entire disc. The total area of the CD was calculated as 10,746µm², with an inner inactive area of 1,661µm², resulting in a total active area of 9,085µm². The calculation of total bits using the formula (224 bits/900µm²) * 9,085µm² yields approximately 2,261 bits, which is inconsistent with the expected storage capacity of around 650MB for a CD. Concerns were raised about the accuracy of the radius measurement of 58.5µm, suggesting it may be incorrect. The discussion highlights the need to verify measurements and calculations to resolve the discrepancy in expected storage capacity.
SarahBoberra
Messages
6
Reaction score
0
We took AFM images of a CD in lab. Manual counting provided that there were 224 bits in the 900µm^2 image I have. Based on this I want to determine the bit-density of the whole CD.

The total active area for the disc is the total area minus the inner inactive are of the disc. The total area was calculated using a radius of 58.5µm and was found to be 10,746 µm^2. The inner inactive area of the disc was found to be 1,661µm^2. Therefore, the total active area of the disk was 9,085µm^2.

Shouldn't the next step be to take (224 bits/900µm^2)*9,085µm^2 to get the total number of bits? For this I get 2,261.156 bits, but it can't be right because it would mean that the whole CD had only 0.00215640640258789MB of storage! I know that CDs have ~650MB of storage. What did I do wrong? Please?
 
Physics news on Phys.org
Radius of 58.5µm doesn't look correct to me. Are you sure you mean µm?
 
the area looks waaaay off!
 

Thread 'Prove that evolution is constant (Provide at least two arguments to support your position)'

I don't get how to argue it. i can prove: evolution is the ability to adapt, whether it's progression or regression from some point of view, so if evolution is not constant then animal generations couldn`t stay alive for a big amount of time because when climate is changing this generations die. but they dont. so evolution is constant. but its not an argument, right? how to fing arguments when i only prove it.. analytically, i guess it called that (this is indirectly related to biology, im...
View full post »

Similar threads

What Did I Do Wrong in CD Bit-density Calculation?
Replies
10
Views
4K
I Atmospheric Density vs Altitude in an O'Neil Cylinder
Replies
1
Views
3K
Method of images, charge q inside conducting sphere
Replies
7
Views
6K
Interesting Telescope Image Recording and Transmission Design Problem Need help
Replies
1
Views
2K

Hot Threads

Recent Insights

Back
Top