electric displacement
Very Low / TechnicalFormal, Academic, Highly Technical
Definition
Meaning
In electromagnetism, a vector field representing the distribution of electric charge needed to generate an electric field within a material, incorporating both free and bound charge effects.
It is a fundamental concept describing the separation of positive and negative charge centers in a dielectric material when subjected to an external electric field. It quantifies how an electric field 'displaces' or polarises the internal charges of a medium, linking the electric field to the charge density via Gauss's law.
Linguistics
Semantic Notes
Not to be confused with 'displacement' in mechanics (movement). Always a technical term with a precise, non-colloquial meaning in physics and engineering contexts. It is often symbolised as D.
Dialectal Variation
British vs American Usage
Differences
Terminology is identical and standardised. Spelling follows national conventions for component words ('electric' vs. rarely 'electrical').
Connotations
None; purely technical.
Frequency
Used with identical technical frequency and no regional preference.
Vocabulary
Collocations
Grammar
Valency Patterns
The electric displacement (D) is defined as...D, the electric displacement, equals ε₀E + P.We must solve for the electric displacement within the material.Vocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Usage
Context Usage
Business
Never used.
Academic
Exclusively used in advanced physics, electrical engineering, and materials science lectures and textbooks.
Everyday
Never used.
Technical
The primary domain. Used in research papers, technical manuals for capacitors/insulators, and in formulating Maxwell's equations for materials.
Examples
By Part of Speech
adjective
British English
- The electric-displacement vector is central to the analysis.
- We studied the electric-displacement boundary conditions.
American English
- The electric-displacement current is a key term in Ampere's law.
- We need the electric-displacement field solution.
Examples
By CEFR Level
- In a capacitor, the electric displacement helps us understand how the insulating material affects the stored charge.
- The professor introduced the concept of electric displacement when discussing materials in electric fields.
- Gauss's law for dielectrics states that the divergence of the electric displacement field equals the free charge density.
- The continuity of the normal component of the electric displacement vector is a crucial boundary condition at dielectric interfaces.
Learning
Memory Aids
Mnemonic
Think: Displacement (D) is what the Electric field (E) does to the material's charges. D = "Displaced charge per area."
Conceptual Metaphor
The electric field 'pushes' or 'displaces' the internal positive and negative charges of a material slightly apart, like a comb separating hairs.
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Do not translate 'displacement' as 'смещение' in its mechanical sense; the standard Russian technical term is 'электрическое смещение' or 'электрическая индукция'.
- Avoid confusing with 'electric induction', though 'электрическая индукция' is an accepted synonym in Russian for this concept.
Common Mistakes
- Using it in a non-physics context.
- Confusing it with 'electric field strength' (E).
- Omitting 'electric' and just saying 'displacement', leading to ambiguity.
- Misspelling as 'electrical displacement' (less common).
Practice
Quiz
What is the primary physical significance of the electric displacement field (D)?
FAQ
Frequently Asked Questions
No. The electric field (E) is the fundamental force field. Electric displacement (D) is a related field that incorporates the effect of the material's polarisation, making Gauss's law simpler when only free charges are considered.
It is central to the integral form of Gauss's law for dielectric materials: ∮ D · dA = Q_free,enc. It also appears in the Maxwell-Ampère law: ∇ × H = J_free + ∂D/∂t.
No, but they are related. 'Electric displacement' is the vector field D. 'Displacement current' is the quantity ∂D/∂t, which appears in Maxwell's equations as a source for magnetic fields.
Most working engineers would rarely use the term 'electric displacement' explicitly in daily design work. They are more likely to use concepts like capacitance, permittivity, and electric field directly. The term is most common in advanced theoretical analysis and academic physics.