UPSC Prelims 2011 · Question 79 of 100

UPSC Prelims 2011 question on Blu Ray vs DVD

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?

1. DVD supports standard Definition video while BD supports High definition Video.

2. Compared to a DVD, the BD format has several times more storage capacity.

3. Thickness of BD is 2.4 mm while that of DVD is 1.2 mm.

Which of the statements given above is/are correct?

Show answer

Answer: B. 1 and 2 only

Correct Answer: 1 and 2 only

Blu-ray Disc and DVD are both optical storage discs, but Blu-ray provides better video quality and much higher storage capacity.

1. DVD supports Standard Definition video, while Blu-ray supports High Definition video — Correct

DVDs are generally used for Standard Definition video.

Blu-ray Discs are designed for High Definition video, giving better picture and sound quality.

2. Blu-ray Disc has much higher storage capacity than DVD — Correct

A single-layer DVD stores about 4.7 GB of data.

A single-layer Blu-ray Disc stores about 25 GB, while a dual-layer Blu-ray can store about 50 GB.

3. Blu-ray Disc is thicker than DVD — Incorrect

This statement is incorrect.

Both DVD and Blu-ray Disc have the same standard thickness of about 1.2 mm and the same diameter of 12 cm.

* DVD uses a red laser of about 650 nm wavelength.

* Blu-ray uses a blue-violet laser of about 405 nm wavelength.

* Shorter wavelength allows Blu-ray to store data more densely.

* Blu-ray has higher storage capacity because data tracks can be packed closer together.

* Blu-ray is commonly used for HD and Full HD video content.

* Do not confuse higher storage capacity with greater physical thickness.

Blu-ray differs from DVD in video quality and storage capacity, but not in physical thickness.

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