displacement current: meaning, definition, pronunciation and examples
C2Technical/Scientific
Quick answer
What does “displacement current” mean?
A quantity appearing in Maxwell's equations that accounts for a changing electric field acting as a current, necessary to complete Ampere's law.
Audio
Pronunciation
Definition
Meaning and Definition
A quantity appearing in Maxwell's equations that accounts for a changing electric field acting as a current, necessary to complete Ampere's law.
A concept in electromagnetism where a time-varying electric field in a region of space (e.g., between capacitor plates) effectively creates a current, even in the absence of moving charges, which is essential for the propagation of electromagnetic waves.
Dialectal Variation
British vs American Usage
Differences
No significant lexical or conceptual differences. Pronunciation and spelling of related terms (e.g., 'metre' vs. 'meter') may vary.
Connotations
Identical technical connotations in both varieties.
Frequency
Extremely low frequency in general language, used identically and exclusively in technical contexts in both regions.
Grammar
How to Use “displacement current” in a Sentence
The displacement current in a capacitor is...Displacement current density is defined as...to account for the displacement currentto introduce the concept of displacement currentVocabulary
Collocations
Examples
Examples of “displacement current” in a Sentence
verb
British English
- The theory displaces the need for a physical connection.
- Maxwell displaced the old understanding by introducing a new term.
American English
- The model displaces the older concept of instantaneous action.
- The new term displaced a major inconsistency in the equations.
adjective
British English
- The displacement current term is crucial.
- We studied the displacement current density.
American English
- The displacement-current concept is key to wireless communication.
- Calculate the displacement current contribution.
Usage
Meaning in Context
Business
Virtually never used.
Academic
Used in advanced undergraduate and postgraduate physics and electrical engineering courses, textbooks, and research papers on electromagnetism.
Everyday
Not used.
Technical
Core term in theoretical electromagnetism, antenna theory, and waveguide physics.
Vocabulary
Synonyms of “displacement current”
Neutral
Weak
Vocabulary
Antonyms of “displacement current”
Watch out
Common Mistakes When Using “displacement current”
- Treating it as a real, measurable flow of charges.
- Omitting it when applying Ampere's law to non-steady-state situations.
- Confusing 'displacement current' with 'displacement' in mechanics.
FAQ
Frequently Asked Questions
No, it is not a flow of charges. It is a mathematical quantity representing the rate of change of the electric displacement field, which has the units of current density and completes Ampere's law.
James Clerk Maxwell introduced it in the 19th century as a crucial addition to Ampere's law, forming a key part of his theory of electromagnetism.
Not directly as you would measure conduction current with an ammeter. Its effects are inferred through the generation of magnetic fields and the propagation of electromagnetic waves.
In its simplest form for a vacuum, it is ε₀ ∂E/∂t, where ε₀ is the permittivity of free space and ∂E/∂t is the rate of change of the electric field.
A quantity appearing in Maxwell's equations that accounts for a changing electric field acting as a current, necessary to complete Ampere's law.
Displacement current is usually technical/scientific in register.
Displacement current: in British English it is pronounced /dɪsˈpleɪsmənt ˈkʌrənt/, and in American English it is pronounced /dɪsˈpleɪsmənt ˈkɜːrənt/. Tap the audio buttons above to hear it.
Learning
Memory Aids
Mnemonic
Think of a capacitor charging: no charges move across the gap, but the changing electric field between the plates 'displaces' the need for a real current, creating a 'displacement current' to complete the circuit in Maxwell's equations.
Conceptual Metaphor
A CHANGING FIELD IS A FLOW (abstracting the property of a changing electric field into the more tangible concept of a 'current' to make the mathematics of electromagnetism consistent).
Practice
Quiz
What physical situation most directly requires the concept of displacement current for analysis?