Question

Unit for measurement of electrical conductivity of milk is

• A. Dynes
• B. Becquerel's
• C. Siemens
• D. Angstrom

Hint:

Physical Units in Dairy Science:
Electrical Conductivity = SIEMENS (S/m or mS/cm).
Viscosity = Poise Centipoise (or Pa$\cdot$s).
Surface Tension = Dynes/cm (or mN/m).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Physical electrochemistry of milk: electrical conductivity ($\kappa$, conductance per unit length) is standardly measured in Siemens per meter ($ ext{S/m}$) or milliSiemens per centimeter ($ ext{mS/cm}$).
Key Formula or Approach:
\[ \text{Electrical Conductivity } (\kappa) = \frac{1}{\rho} \quad \implies \quad \text{SI Unit: } \mathbf{Siemens \text{ per meter (S/m)}} \quad (\text{or } \text{mS/cm} / \text{mho}) \]

Step 2: Detailed Explanation:
In the physical properties and electrical conductivity of milk:
1. Electrical Conductivity ($\kappa$): Measures the capacity of milk to conduct an electric current, governed primarily by soluble dissolved mineral electrolytes ($\text{Na}^+, \text{K}^+, \text{Cl}^-$). In healthy bovine milk, electrical conductivity ranges between $4.0\text{ to 5.5\text{ mS/cm}$ ($0.40 - 0.55\text{ S/m}$)} at $25^\circ ext{C}$ (rising to $> 6.0\text{ mS/cm}$ in mastitic milk).
2. SI Unit of Conductance and Conductivity: The SI unit of electrical conductance is Siemens (S) (formerly mho $\Omega^{-1}$), and electrical conductivity is expressed in Siemens (C) (or Siemens per meter $\text{mS/cm}$).
3. Dynes: Force; Becquerel: Radioactivity; Angstrom: Wavelength/Distance.

Step 3: Final Answer:
Hence, the unit for measurement of electrical conductivity is Siemens, matching option (C).