CD Working

• CD stands for Compact Disk.
• CD is 12cm in Diameter
• Contains 4 Layers
• Label
• Plastic
• Aluminium Sheet
• Poly-Carbonate Sheet
• Data is stored in the form of the circular spirals.

CD Working:

• Data of the CD is read by the Laser Beam and Sensor.
• Laser Beam hits the CD and Reflects on to the sensor.
• If Laser light hits the Sensor there is data, if not there is no data.
• There three types of CDs
• CD-ROM
• CD-R
• CD-RW

CD-ROM:

• CD-ROM is the Compact Disk which can only readable.
• CD-ROM data is stored while making the CD.
• Data in the CD is noticed by Bumps on the CD.
• Laser hits the flat surface reflected back on to sensor.
• Laser hits the bump surface, reflected didn't hits the sensor.

CD-R:

• CD-R is the Recordable Compact Disk, which we write memory in the disk.
• CD-R beam consists of Dye layer in between the Polycarbonate Plastic and Aluminium Sheet.
• Data needed place is burnt using laser and non data place is leaved unburnt.
• Data reading is same as the CD-ROM where ever the Dye is not present reflected back on to sensor.

CD-RW:

• CD-RW is Rewritable Compact Disk,in which we can erase and write data.
• In CD-RW Dye Layer is replaced by Phase Change Material.
• Phase Change Layer Material is capable of getting back into its shape by heating it to some other extent.
• Reading and Writing working principle same as CD-R and CD-ROM.