Instrumentation & Measurements: Match Device to Application List I A. Digital counter B. Schering bridge C. Megger D. Spectrum analyser List II Measurement of harmonics (spectral components) Measurement of frequency Measurement of loss angle of dielectric Measurement of insulation resistance

Introduction / Context:
This question matches classic instruments to what they measure, spanning frequency counting, dielectric testing, insulation-resistance measurement, and spectral analysis. Mastery of these pairings aids in selecting the right tool for RF, power, and materials labs.

Given Data / Assumptions:

• Digital counter measures repetitive events to compute frequency.
• Schering bridge evaluates capacitors and dielectrics, yielding loss angle (dissipation factor).
• Megger (insulation tester) applies high DC voltage to measure very high resistances.
• Spectrum analyser displays amplitude versus frequency, revealing harmonics and spurs.

Concept / Approach:

Use each instrument’s defining capability: counters time zero-crossings/pulses, bridges compare impedances to extract dielectric loss, meggers characterize insulation via megohm-scale resistance, and spectrum analysers resolve frequency-domain content including harmonics and intermodulation products.

Step-by-Step Solution:

Verification / Alternative check:

Typical lab procedures: frequency counter on a known RF source; Schering bridge datasheets emphasize tan δ; meggers specify ranges in MΩ to GΩ; spectrum analysers display multi-tone spectra showing harmonics clearly.

Why Other Options Are Wrong:

Assigning the megger to “harmonics” or the counter to “loss angle” ignores instrument physics. The Schering bridge targets dielectric characterization, not frequency counting.

Common Pitfalls:

Confusing an oscilloscope (time-domain) with a spectrum analyser (frequency-domain); using a multimeter for insulation tests where a megger is appropriate due to higher test voltage.

Final Answer:

A-2, B-3, C-4, D-1