Dielectric loss and complex polarizability When a dielectric is subjected to an alternating electric field, the material absorbs energy from the field. This loss is represented by the imaginary part of the complex polarizability. Decide if this statement is correct.

Introduction / Context:
In AC fields, dielectric materials exhibit frequency-dependent behavior often described by complex quantities: complex permittivity ε* and complex polarizability α*. The real part stores energy; the imaginary part accounts for dissipative loss (heat generation).

Given Data / Assumptions:

• Linear time-harmonic fields with angular frequency ω.
• Complex polarizability α*(ω) = α′(ω) − j α″(ω).
• No significant conduction current contribution (which would add σ terms to effective loss).

Concept / Approach:
The power loss density in a dielectric can be related to the out-of-phase component of polarization relative to the electric field. That out-of-phase component is captured by the imaginary part of α* or equivalently by ε″, the imaginary part of the complex permittivity ε* = ε′ − j ε″. Therefore, α″ directly represents energy dissipation associated with polarization mechanisms.

Step-by-Step Solution:
Express complex polarization: P = N α* E for N polarizable units per volume.Decompose α* into real and imaginary parts: α* = α′ − j α″.Recognize that the quadrature (loss) component contributes to average power absorbed during a cycle.Hence, the imaginary part α″ represents dielectric loss due to polarization lag.

Verification / Alternative check:
Loss tangent tan δ = ε″ / ε′ relates the imaginary and real parts of permittivity; calorimetric or bridge measurements confirm that ε″ and α″ correlate with heating in dielectrics.

Why Other Options Are Wrong:
Limiting validity to “very low frequency” or “only at resonance” is incorrect—loss can exist over broad bands, peaking near relaxation or resonance. Conductors involve additional ohmic loss but the statement concerns dielectrics.

Common Pitfalls:
Confusing dielectric loss with conduction loss; both can coexist but are distinct mechanisms.

Final Answer:
True