Unit 3

• Match Instrumentation Transducers with Working Principles:
• Strain Gauge $\longrightarrow$ (I) Mechanical deformation to electrical signal: Piezoresistive sensor whose electrical resistance alters proportionally to mechanical strain ($R \propto \Delta L$).
• Thermocouple $\longrightarrow$ (II) Temperature measurement via Seebeck effect: Generates an electromotive force (EMF) at the junction of two dissimilar metallic conductors proportional to temperature difference.
• LVDT (Linear Variable Differential Transformer) $\longrightarrow$ (III) Precision linear displacement: Inductive transducer converting core linear mechanical position into differential secondary AC voltage with extreme linearity.
• Piezoelectric Transducer $\longrightarrow$ (IV) Electrical charge under mechanical pressure/vibration: Asymmetric crystal (quartz, PZT) generating electric surface charge in response to applied dynamic stress.
• Conclusion: A-I, B-II, C-III, D-IV (Option 2).

Correct option: (2) AA,B-I,C-I,D-V.

• Spectral Emission of Tungsten Filament Lamps:
• Spectrophotometric Light Source:
• tungsten-halogen or tungsten filament incandescent lamp emits continuous blackbody thermal radiation spanning the visible and near-infrared range ($320 - 2,500\text{ nm}$).
• Deuterium arc lamps are used for the ultraviolet (UV) region ($190 - 380\text{ nm}$).
• Conclusion: Visible Range (Option 2).

Correct option: (2) Visible Range

• Absorbance vs. Percent Transmittance in Spectrophotometry:
• Beer-Lambert Law Linearity:

• Absorbance ($A$) is directly proportional to analyte concentration ($c$), yielding linear calibration curves.
• Percent Transmittance ($\%T = 100 \times 10^{-A}$) exhibits a non-linear exponential decay with concentration, complicating quantitative determinations.
• Conclusion: Because absorbance is proportional to the concentration of the analyte, whereas %T is not (Option 3).

Correct option: (3) Because absorbance is proportional to the concentration of the analyte, whereas %T is not

• Beer-Lambert Concentration Calculation:
• Given Parameters:
• Absorbance: $A = 0.54$
• Path length: $l = 1\text{ cm}$
• Molar absorption coefficient: $\epsilon = 6.4 \times 10^3\text{ L}\cdot\text{mol}^{-1}\cdot\text{cm}^{-1}$
• Concentration ($c$):

• Conclusion: 0.084 mM (Option 2).

Correct option: (2) 0.084 mM