ITPEC IP October 2024 Question 1
Which of the following is the combination of terms or phrases to be inserted into blanks A through C in the description below concerning a method for representing information?
Data that represents information by using a continuous, variable physical volume (length, angle, voltage, etc.) is called A data, and data that represents information by using discrete numerical values is called B data. A CD that is used for the distribution of music and songs is an optical disc medium that stores information as C data.
Explanation
A: analog, B: digital, C: digital — the question tests the two ways of representing information and which one a music CD uses.
Data that represents information with a continuously varying physical quantity such as length, angle or voltage is analog data (blank A). Data that represents information with discrete numerical values is digital data (blank B).
A music CD samples the sound wave at fixed intervals and stores each sample as a binary number, read optically from the disc. It therefore stores digital data (blank C); the player converts the numbers back into an analog signal for the speakers.
Answer (b)
Why not others:
- •(a) — defines A and B correctly but calls the CD analog, confusing the analog sound it reproduces with the discrete samples it stores
- •(c) and (d) — swap the two definitions: a continuous quantity is analog, and discrete numerical values are digital
Key rule: Continuous physical quantity = analog; discrete numerical values = digital. CDs, DVDs, USB memory and other computer media store digital data even when the content began as analog sound or images.
Basic Theory · AI-written, may contain errors
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