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Showing 61–90 of 1709 reference entries

Physics · MeasurementElectric current

Current measures charge crossing a chosen surface per unit time.

DefinitionPhysicsElectric field and force

An electric field assigns force per unit test charge.

DefinitionPhysicsMagnetic force on a moving charge

Magnetic force depends on charge motion relative to the field.

ModelPhysicsOhm's law and its domain

A linear current-voltage relation requires suitable conditions.

Empirical findingPhysicsFirst law of thermodynamics

Keep the heat and work sign convention explicit in an energy balance.

ModelPhysicsSecond law: isolated-system entropy

Apply entropy increase to the whole isolated system.

ModelPhysics · ChemistryIdeal-gas equation of state

A simple gas model relates pressure, amount, volume and temperature.

ModelPhysicsPhoton energy and frequency

One photon's energy is proportional to its frequency.

ModelPhysics · Mathematics & logicInvariant spacetime interval

Lorentz transformations preserve a combined space-time separation.

ModelPhysicsNewton's third law

Interaction forces act on different bodies in equal and opposite pairs.

ModelPhysicsAngular momentum and torque

Torque changes angular momentum about a specified origin.

ModelPhysicsHydrostatic pressure

Static fluid pressure rises with depth under gravity.

ModelPhysicsArchimedes' buoyancy principle

The hydrostatic upward force equals displaced-fluid weight.

ModelPhysicsMaxwell equations in free space

Four field equations connect electric and magnetic fields with charge and current.

ModelPhysicsSchrödinger time evolution

A quantum wavefunction evolves according to its Hamiltonian.

ModelPhysicsBorn position probability

A normalized wavefunction assigns probabilities to position intervals.

ModelPhysics · MeasurementElementary charge

The elementary charge has an exact SI numerical value.

DefinitionPhysics · MeasurementBoltzmann constant

The Boltzmann constant has an exact SI numerical value.

DefinitionMeasurement · Chemistry · PhysicsAvogadro constant

The mole is linked to a specified number of entities.

DefinitionMeasurement · PhysicsSI defining luminous efficacy

A specified frequency fixes the photometric SI reference.

DefinitionChemistryAtoms and elemental identity

The proton count of an atomic nucleus identifies its chemical element.

DefinitionChemistryIsotopes and mass number

Isotopes share a proton count but have different neutron counts.

DefinitionChemistryPeriodic organization of the elements

Atomic-number order reveals recurring patterns in electron structure and chemical properties.

ModelChemistryChemical bonds

Bonding describes interactions that bind atoms into molecules or extended structures.

DefinitionChemistry · MeasurementMole and amount of substance

The mole counts specified entities using the exact Avogadro constant.

DefinitionChemistryReaction stoichiometry

Balanced coefficients relate the amounts consumed and produced by a reaction.

MethodChemistryBalancing atoms and electric charge

A chemical equation must preserve each element's atom count and the total charge.

MethodChemistryDynamic chemical equilibrium

At equilibrium, opposing reactions continue without net composition change.

ModelChemistryBrønsted acids and bases

In the Brønsted description, an acid donates a proton and a base accepts it.

DefinitionChemistryGibbs energy and thermodynamic direction

Gibbs-energy change distinguishes thermodynamic favourability from reaction speed.

Model
DefinitionSource checked

Electric field and force

Physics

An electric field assigns force per unit test charge.

Key knowledge

The electric field at a point is defined through the electric force on a sufficiently small test charge: F_electric = qE. It is a vector field; the sign of q affects the force direction.

Values and equations

F_electric = qE

F_electric
Electric force vector N
q
Signed test charge C
E
Electric field vector N C⁻¹

Conditions and scope

  • The test charge should not significantly rearrange the source distribution.
  • The electric force is distinguished from magnetic and other forces.
Sources · 3

References

Sources retain their recorded scope. A source link alone does not establish verification of every statement.

  1. University Physics, volume 2: Electric FieldSamuel J. Ling, Jeff Sanny and William Moebs / OpenStax, Rice UniversityTextbook chapteropenstax.orgRead source
  2. College Physics 2e (2022), §18.4: Electric Field—Concept of a Field RevisitedPaul Peter Urone and Roger Hinrichs — OpenStax, Rice University (2022)Textbook chapteropenstax.orgRead source
  3. Electric Charges and Fields · Physics (2026–27 reprint)National Council of Educational Research and Training (NCERT)Textbook chapter · PDFncert.nic.inRead source

Evidence and review

OpenStax 5.4, equations 5.3–5.4 and test/source distinction.

2026-10-10 · Local electric field-force definition only; no particular source geometry or full electromagnetic solution is supplied.

Foundational review

2026-10-10 · Fresh primary-source inspection of the complete compact record, including every statement, equation, quantity and material condition, followed by independent AI editorial review. This check does not certify all linked lessons or every passage of every cited publication.

Sources from other places

Agreement within this scope

Electric field is electric force per small test charge, with the test charge sufficiently small to avoid disturbing source charges.

For a moving charge the magnetic contribution must be considered separately.

Related reference entries

Explore relationships within this area of study and its connections to other areas.

Showing 1–5 of 5 relationships

Scientific relationships · 5 / 5

The relationship type describes the connection. Its linked statements, sources and conditions define the scope.

  1. Related to
    Relationship sources · 1

    The electric field defines the electric contribution to force on a test charge.

  2. Uses definition
    Relationship sources · 2

    E is the electric field in the classical free-space field equations; this is not a material D/H constitutive law.

  3. Related to
    Relationship sources · 1

    Linked statements

    • For a linear capacitor of fixed geometry and dielectric response, charge magnitude Q is proportional to potential-difference magnitude ΔV: Q = CΔV. C is the capacitance.

    Fixed-geometry electric potential difference and separated conductor charge.

  4. Related to
    Relationship sources · 2

    Linked statements

    • In vacuum electrostatics, a point charge q at r′ produces E(r)=q(r−r′)/(4πε₀|r−r′|³). Extended charge fields follow the corresponding integral over ρ(r′); scalar potential is the integral of ρ/(4πε₀|r−r′|), with the chosen infinity boundary condition.

    Static charge distribution supplies the field in the electrostatic force definition.

  5. Uses definition
    Relationship sources · 2

    Linked statements

    • In electrostatics, potential difference V_B−V_A is the potential-energy change of a small fixed test charge divided by that signed charge: ΔU=qΔV. Equivalently ΔV=−∫_A^B E·dr and E=−∇V. Potential has an arbitrary additive reference, while differences determine work. A volt is a joule per coulomb; voltage is not itself stored energy.

    This relation concerns the stated electric potential, voltage and potential energy claim and its conditions; it does not assert an unqualified prerequisite or an additional theorem.

Entry detailsPermanent link to this entry ↗
Record identity
physics-electric-field
Revision
core.1
Structured reference record
Essential core · first collection · University core expansion