Optical Disk - Notes for Exam
✅ Definition
An optical disk is a storage medium from which data is read and written using laser light.
📌 Types of Optical Disks
| Type | Description | Storage Capacity |
|---|---|---|
| CD-ROM (Compact Disc - Read Only Memory) | Data written once, read many times | ~700 MB |
| CD-R (Recordable) | Write once, can't erase | ~700 MB |
| CD-RW (Rewritable) | Can be erased and reused | ~700 MB |
| DVD-ROM (Digital Versatile Disc) | Higher capacity than CD | ~4.7 GB |
| DVD-R / DVD+R | Write once | ~4.7 GB |
| DVD-RW / DVD+RW | Rewritable version of DVD | ~4.7 GB |
| Blu-ray Disc | High definition video & data | 25 GB (single layer), 50 GB (dual layer) |
🔍 Important Points
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Optical disks are portable and durable.
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Data is read using a laser beam.
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Optical disks are slower than hard drives or SSDs.
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Commonly used for media, software installation, and backups.
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Blu-ray uses blue-violet laser, while CD/DVD uses red laser.
💡 Advantages
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Portable and easy to store.
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Relatively inexpensive.
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Good for long-term storage (read-only).
⚠️ Disadvantages
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Limited storage capacity.
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Slower data access speed.
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Easily scratched or damaged.
📘 MCQs on Optical Disk (with answers)
Q1. Which of the following is an optical storage device?
A) Hard disk
B) Pen drive
C) CD-ROM
D) RAM
✅ Answer: C
Q2. What is the typical storage capacity of a standard CD-ROM?
A) 4.7 GB
B) 700 MB
C) 1.44 MB
D) 2 TB
✅ Answer: B
Q3. Which of the following can be rewritten multiple times?
A) CD-R
B) CD-ROM
C) CD-RW
D) DVD-R
✅ Answer: C
Q4. Which laser color is used in Blu-ray Discs?
A) Red
B) Infrared
C) Blue-violet
D) Green
✅ Answer: C
Q5. DVD stands for:
A) Digital Virtual Device
B) Direct Video Disk
C) Digital Versatile Disc
D) Data Visual Device
✅ Answer: C
Q6. What is the capacity of a single-layer Blu-ray Disc?
A) 700 MB
B) 4.7 GB
C) 25 GB
D) 50 GB
✅ Answer: C
Q7. Which of the following is not a feature of optical storage?
A) Uses laser technology
B) Portable
C) Magnetic storage
D) Read-only or rewritable
✅ Answer: C
Q8. Which type of disk allows data to be written only once?
A) CD-R
B) CD-RW
C) Blu-ray RW
D) DVD-RW
✅ Answer: A