Understanding Resolution in Measurement

The question asks for the term that defines the minimum input value required to cause a noticeable or detectable change in the output of a system, especially when starting from zero output. Let's analyze the given options:

Defining Resolution

Resolution is defined as the smallest change in the input quantity that can be detected by the system or instrument, resulting in a corresponding change in the output. In simpler terms, it's the minimum input step that the system can respond to. This directly matches the question's description of the minimum input necessary for a detectable change from zero output.

Analyzing Other Options

• Least Count: This term is typically used for measuring instruments and refers to the smallest measurement that can be accurately read from the instrument's scale. While related to sensitivity, it's about the instrument's display capability rather than the input needed to trigger an output change in a system.
• Drift: Drift refers to a slow, continuous change in the output signal of a system over time, even when the input remains constant. This is an error factor, not the minimum input required for a detectable change.
• Threshold: A threshold is a level that must be exceeded for an event to occur or a signal to be recognized. While similar to resolution, the term 'resolution' is more specifically used in the context of input-output relationships where a change in input causes a change in output. 'Threshold' might refer to a minimum *signal level* rather than the minimum *change* in input. Given the specific wording about input causing an output change, resolution is the more precise term.

Conclusion

Based on the definitions, Resolution is the correct term for the minimum input value needed to cause a detectable change from zero output. It represents the smallest input increment the system can effectively respond to.