COMPUTER FUNDAMENTALS

Detailed explanation-1: -CD-RW and DVD-RW discs are primarily used when you want to burn data or music and at a later time erase the CD or DVD and burn updated or new files to it. CD-RW discs can be erased and burned as many as a thousand times, DVD-RW perhaps a hundred.

Detailed explanation-2: -In a CD reader, the source of light is a semiconductor laser at a fixed wavelength of 780 nm. Note that 780 nm is in the infrared and not visible to the human eye; you can’t see the CD player’s laser shining on the CD with your naked eye.

Detailed explanation-3: -A CD is a mirrored surface with spiral tracks or pits. These tracks are evenly spaced and diffract the sunlight (separating the colors). Because the CD’s surface is mirrored, the light is reflected to your eye.

Detailed explanation-4: -A laser is used to transfer digital data (a long sequence of ones and zeros) to this disc by literally burning small ‘pits’ into the surface, with untouched areas (called ‘lands’) representing ones and burned areas representing zeros.