Q. A new optical disc format known as the Blu-ray Disc (BD) is becoming popular. In what way is it different from the traditional DVD?
- DVD supports Standard Definition video while BD supports High Definition video.
- Compared to a DVD, the BD format has several times more storage capacity.
- Thickness of BD is 2.4 mm while that of DVD is 1.2 mm.
Which of the statements given above is/are correct? (UPSC Prelims 2011)
Answer:
1 and 2 only
Notes: The correct answer is
1 and 2 only. Blu-ray Discs (BD) were designed to supersede the DVD format by offering significantly higher data density and better video resolution through the use of a different laser technology.
- Video Resolution (Statement 1 is Correct): Traditional DVDs are limited to Standard Definition (SD) resolution (typically 480i or 576i). Blu-ray discs were specifically engineered to handle High Definition (HD) video, supporting resolutions of 720p, 1080p, and even 4K UHD in later versions.
- Storage Capacity (Statement 2 is Correct): Due to the use of a shorter wavelength blue-violet laser (405 nm compared to the red 650 nm laser used for DVDs), data can be packed much more tightly. A standard single-layer DVD holds 4.7 GB, while a single-layer Blu-ray disc holds 25 GB—more than five times the capacity.
- Physical Thickness (Statement 3 is Incorrect): Both Blu-ray discs and DVDs have exactly the same physical thickness of 1.2 mm. While the internal layer structure differs, the overall disc dimensions are identical to ensure they fit into standard disc drive slots.