In this instrument analogy, “Ammeter is to Current as ______ is to ______”. Choose the instrument and physical quantity pair that stands in the same measuring instrument to quantity measured relationship.

Introduction / Context:
This analogy tests knowledge of basic scientific instruments and the physical quantities they measure. The pair “Ammeter : Current” links an instrument (ammeter) with the quantity it measures (electric current in amperes). To complete the analogy, we must choose another pair where the first word is a measuring instrument and the second word is the physical quantity it is designed to measure. Recognising these instrument quantity pairs is common in general science questions.

Given Data / Assumptions:

• Example pair: Ammeter → Current. span style="display:block;">• Target pair: ? → ? • Options: Scale : Speed, Seismograph : Density, Barometer : Mass, Anemometer : Wind. • We assume standard textbook definitions of scientific instruments and their primary uses.

Concept / Approach:
The relationship in the example is clearly “measuring instrument : quantity measured”. An ammeter is used to measure electric current. We must look for an option where the first term is a recognised scientific instrument and the second is the proper physical quantity associated with that instrument. Among the choices, an anemometer is a device designed specifically to measure wind speed or wind flow, so the pair “Anemometer : Wind” matches the pattern exactly.

Step-by-Step Solution:
Step 1: Analyse the example pair. An ammeter is connected in an electric circuit to measure the current flowing through it, usually in amperes. Step 2: Evaluate each option. Scale : Speed – A scale is normally used to measure weight or mass, not speed. Seismograph : Density – A seismograph records seismic waves generated by earthquakes, not material density. Barometer : Mass – A barometer measures atmospheric pressure, not mass. Anemometer : Wind – An anemometer is used to measure wind speed or velocity and is directly associated with wind. Step 3: Only Anemometer : Wind fits the pattern of “instrument : quantity measured”.

Verification / Alternative check:
To verify, restate each pair as “instrument that measures X”. Ammeter measures current, anemometer measures wind, barometer measures pressure, seismograph measures seismic activity, and scale measures weight or mass. Thus, only “Ammeter : Current” and “Anemometer : Wind” share the same type of relationship. The other options link instruments to incorrect or mismatched quantities.

Why Other Options Are Wrong:
• Scale : Speed – Incorrect because speed is measured by a speedometer or similar device, not by a weighing scale. • Seismograph : Density – Seismograph outputs wave information, not density; density measurements require other methods. • Barometer : Mass – Barometer measures atmospheric pressure; mass is measured with balances or scales.

Common Pitfalls:
A frequent error is to choose an instrument paired with any scientific sounding term instead of checking if it is truly the quantity measured by that instrument. Remember to recall basic instrument definitions: ammeter current, voltmeter voltage, barometer pressure, thermometer temperature, and anemometer wind. This mental list helps you quickly recognise the correct pair in such questions.

Final Answer:
The related word pair that correctly completes the analogy is Anemometer : Wind.