5.1 (new)

Question 1

CDs and DVDs are described as?

Answer 1

optical storage devices

Question 2

Laser light is used to?

Answer 2

read and write data to and from the surface of the disk

Question 3

Both CDs and DVDs use?

Answer 3

a thin layer of metal alloy or light-sensitive organic dye to store the data.

Both use a single, spiral track which runs from the centre of the disk to the edge.

Question 4

What happens when a disk spins?

Answer 4

the optical head moves to the point where the laser beam ‘contacts’ the disk surface and follows the spiral track from the centre outwards

Question 5

As with a HDD, a CD/DVD is?

Answer 5

it is divided into sectors allowing direct access to data. In the case of HDD, the outer part of the disk runs faster than the inner part of the disk.

Question 6

how is the data read in optical media?

Answer 6

The data is stored in ‘pits’ and ‘lands’ on the spiral track.

A red laser is used to read and write the data.

CDs and DVDs can be designated ‘R’ (write once only) or ‘W’ (can be written to or read from many times).