Identifying analog quantities in measurement and control Which statement correctly characterizes an analog quantity in electronics and instrumentation?

Introduction / Context:
Analog signals are ubiquitous in sensors and control systems. Distinguishing analog from digital is foundational for choosing conversion (ADC/DAC) methods, filters, and signal conditioning.

Given Data / Assumptions:

• We compare general properties of analog versus digital signals.
• No special transfer function (like logarithmic) is implied for all analog signals.

Concept / Approach:
An analog quantity can take any value within a continuous interval (for example, 0 to 5 V, or −10 to +10 V). In contrast, digital quantities take values from a discrete set (quantized steps). While some analog systems have logarithmic responses, that is not a universal trait of “analog.”

Step-by-Step Solution:

Verification / Alternative check:
A temperature sensor producing 0–10 V is analog because it can output infinitely many voltages in that range; a 10-bit ADC version of that signal would be discrete (1024 steps).

Why Other Options Are Wrong:

• Discrete levels / finite steps: These are digital properties.
• Logarithmic response: Specific to certain analog elements (e.g., dB scales, diode I-V), not a defining characteristic.

Common Pitfalls:

• Assuming analog implies nonlinearity; analog can be linear or nonlinear.

Final Answer:
It has a continuous set of values over a given range.