INPUTOUTPUT AND STORAGE DEVICES
STORAGE DEVICES HARD DISK SSD AND FLASH MEMORY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Red
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Blue
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Green
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Colorless
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Detailed explanation-1: -In the case of CD-R, an infrared laser with a wavelength of 780 nanometers (nm) is employed, while DVD-R uses a red laser with a wavelength of 635 nm.
Detailed explanation-2: -The lasers uses in DVD players operate at a wavelength of 650 nm (instead of 780 nm in a CD). 650 nm is visible for the human eye and corresponds to a red color: you’ve probably noticed that there is a red light shining onto the DVD surface inside the player.
Detailed explanation-3: -No, CDs and DVDs require different types of laser. To be clear, when you say “DVD-R", are you referring to the physical disk or the drive used to write it? Just a note for you, you usually can write to a CD-R using a DVD-R drive.
Detailed explanation-4: -A dvd/CD-ROM works with lasers because normal lightwaves are too big. With a DVD, you use a red laser beam to read and write the information. The information you write onto the disk can’t be smaller than the size of the beam.