Question

The thickness of a CD ROM Is..........mm approximately.

• A. 1.22
• B. 1.5
• C. 0.66
• D. None of these

Hint:

The physical base dimensions of standard optical discs (CDs, DVDs, Blu-rays) are universally identical to ensure backward compatibility across different optical disk drives: 120 mm in overall diameter and 1.2 mm in thickness.

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
The question asks for the standard or approximate physical thickness of a CD ROM in millimeters.


Step 2: Detailed Explanation:
According to the foundational physical specifications (the Red Book standard) for optical discs like CDs, the physical dimensions are strictly predefined for global manufacturing consistency.
A standard CD is exactly 120 mm in diameter and exactly 1.2 mm in thickness.
Looking at the provided options, 1.22 mm is very close to 1.2 mm but is technically inaccurate for a strict standard.
Since 1.2 mm is the precise industry standard and none of the numerical options (1.22, 1.5, 0.66) completely match this established value, the most accurate multiple-choice selection is "None of these".


Step 3: Final Answer:
The exact standard thickness of a CD ROM is 1.2 mm. Therefore, none of the given exact numeric options are completely correct.