Definition of a digital quantity: does it assume discrete values? Evaluate the statement: “A digital quantity has a discrete set of values.” Decide whether this captures the essence of digital representation.
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ACorrect
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BIncorrect
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COnly true for voltage, not time
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DOnly true below 1 kHz
Answer
Correct Answer: Correct
Explanation
Introduction / Context:Digital versus analog is a core distinction in engineering. A digital quantity is one that assumes values from a countable set, typically finite within a given word length. This item checks your understanding of that definition and its implications for measurement and computation.
Given Data / Assumptions:
- Digital systems represent information with discrete symbols (bits) aggregated into words.
- A fixed word length implies a finite set of representable codes at any instant.
- Quantization maps continuous variables to discrete codes.
Concept / Approach:By definition, digital quantities are discrete. An n-bit word encodes 2^n possible values (or states). In contrast, analog quantities vary continuously within ranges. The discreteness underpins quantization error, sampling theory, and noise immunity advantages of digital processing.
Step-by-Step Solution:
Differentiate digital (discrete) from analog (continuous).Relate to word length: n bits → 2^n representable codes.Recognize effects: quantization error and stepwise resolution.Conclude the statement is correct.Verification / Alternative check:Consider a 10-bit ADC: it outputs one of 1024 codes for any input, illustrating discreteness.
Why Other Options Are Wrong:
Incorrect: Opposes the fundamental definition.Voltage/time/frequency qualifiers: Discreteness applies to the represented variable regardless of domain; sampling in time is also discrete when clocked.Common Pitfalls:Assuming digital waveforms are “square analog” and thus continuous; their representation and interpretation are discrete even if the physical waveform has finite rise time.
Final Answer:Correct