chp 3.2

Question 1

CDs use

Answer 1

lasers with a wavelength of 780 nanometres.

Question 2

Uses of CD-R and DVD-R

Answer 2

» Home recordings of music (CD-R) and films (DVD-R).
» Used to store data to be kept for later use or to be transferred to another
computer.

Question 3

Advantages of CD-R and DVD-R

Answer 3

» Cheaper medium than RW disks.
» Once burned (and finalised) they behave like a ROM.

Question 4

Disadvantages of CD-R and DVD-R

Answer 4

» Can only be recorded once;
» Not all CD/DVD players can read CD-R/DVD-R.

Question 5

Uses of CD-RW/DVD-RW

Answer 5

» Used to record television programmes which can be recorded over, time and
time again
» Used in CCTV systems.
» Can be used as a backup device for files and data.

Question 6

Advantages of CD-RW/DVD-RW

Answer 6

» Can be written over many times.
» Can use different file formats each time it is used.
» Not as wasteful as R format

Question 7

Disadvantages of CD-RW/DVD-RW

Answer 7

» Can be relatively expensive media.
» Possible to accidentally overwrite data.

Question 8

Uses of CD-ROM/DVD-ROM

Answer 8

» They are a permanent method of data
storage.
» CD-ROM is used to store music files and to store software, computer games
and reference software
» DVD-ROM has much larger storage and is used to store films
» CD-ROMs and DVD-ROMs used in applications where there is a real need to
prevent the deletion or overwriting of important data.

Question 9

Advantages of CD-ROM/DVD-ROM

Answer 9

less expensive than hard disk drive systems.

Question 10

Disadvantages of CD-ROM/DVD-ROM

Answer 10

data transfer rate/data access time is slower than for hard disks.