What is the primary difference between a CD and a DVD?
A. CDs store more data than DVDs
B. DVDs use a shorter wavelength laser, allowing higher density
C. DVDs are older technology
D. CDs are read-only; DVDs are rewritable
Answer: Option B
Solution (By JKSSB Mock Tests)
DVDs use a shorter wavelength laser (650 nm vs 780 nm for CDs), which allows smaller pits and tighter tracks, resulting in higher storage capacity (4.7 GB vs 700 MB).
Explanation:
Magnetic tape offers the lowest cost per gigabyte among these, making it ideal for archival and backup. HDDs are also used but tape is cheaper for large volumes.
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