Thermal, Optical & Electrical Properties of Grains
Subtopic: Dielectric properties of grains in microwave drying
Question Statement:
In microwave and dielectric heating of agricultural produce, the dielectric loss factor ($\epsilon''$) is a measure of the material's ability to:
Options:
(A) Dissipate absorbed electromagnetic field energy into thermal heat
(B) Store electrical electrostatic energy without heating
(C) Reflect incident radio-frequency radiation like a mirror
(D) Conduct electric DC direct current without resistance
Answer Key:
A
Step-by-Step Solution & Explanation
In complex relative permittivity $\epsilon^* = \epsilon' - j \epsilon''$:
- The dielectric constant $\epsilon'$ measures the ability to store electric energy.
- The dielectric loss factor $\epsilon''$ quantifies the rate of dissipation of electromagnetic field energy into internal kinetic thermal heat via dipole oscillation and ionic conduction.