Published
electrical resistance
vr.tr.electrical-resistance · thing-q25358
Let an agent explain electrical resistance, its units, laws and measurement, distinguish resistance from resistivity, impedance and conductance, and support calculation and teaching.
Thing Registry Cross-cutting context XCT.QLT
Bundle → Layer → Finding → QuestionsClassifiersWhat it isWhy it existsDistinguishing featuresWhat robots and AI may and may not doMoral aspectsOwnersLinks to other meta-modelsIdentity and identifiersDirect propertiesRecognitionCapabilities and actionsHazards and failure modesStandards and interfacesContext of useSources
Bundle → Layer → Finding → Questions Filled
4 bundles · 8 layers · 8 findings · 16 questions
Concept What resistance is.
Definition
Definition and law.
Definition
Definition.
- What is electrical resistance, and what does Ohm law state and not state? definition
- Is the question about resistance, resistivity, impedance or conductance? boundary
Factors
What determines it.
Factors
Factors.
- How do material, length, cross-section and temperature determine resistance? definition
- Which entry fits resistivity? action
Calculate Circuits and calculation.
Circuits
Series and parallel.
Circuits
Circuits.
- How are resistances combined in series and parallel, and how is a circuit solved? action
- What is the result for the circuit in question? measurement
Power
Power and heating.
Power
Power.
- How does resistance relate to power dissipation and heating? definition
- Which entry fits Joule heating? action
Measure Measurement.
Methods
Methods.
Methods
Methods.
- How is resistance measured, from ohmmeters to four-terminal sensing? measurement
- What accuracy and sources of error apply? measurement
Components
Resistors.
Components
Components.
- How are resistors specified and marked? provenance
- Which entry fits resistors? action
Learn Physics and teaching.
Physics
Microscopic origin.
Physics
Physics.
- What is the microscopic origin of resistance, and what are superconductivity and non-ohmic behaviour? provenance
- Which entry fits superconductivity? action
Teach
Teaching.
Teach
Teaching.
- How is resistance taught, and which misconceptions arise? provenance
- Which references are standard? provenance
Classifiers Filled
- Family
- Thing Registry
- Category
- Cross-cutting context
- Entry kind
- thing
- Plane
- XCT
- Domain
- XCT.QLT
- Other names and narrower kinds
- impedance, sheet resistance, characteristic impedance, input impedance, output impedance, transepithelial electrical resistance, Thévenin resistance, insulation resistance, internal resistance, contact resistance, equivalent series resistance, negative resistance
What it is Filled
The opposition a material or component offers to the flow of electric current, defined as voltage divided by current and measured in ohms; resistance depends on material, dimensions and temperature, and the related quantity impedance extends the idea to alternating current by including reactance, while resistivity describes the material independent of shape.
Why it exists Filled
Let an agent explain electrical resistance, its units, laws and measurement, distinguish resistance from resistivity, impedance and conductance, and support calculation and teaching.
Distinguishing features Filled
- Ratio of voltage to current
- Ohmic and non-ohmic behaviour
- Temperature dependence
- Scalar, unlike complex impedance
What robots and AI may and may not do Filled
Must not
- Measure or work on live circuits outside the safety procedures that apply.
- Ignore high-resistance connections that are heating up.
- Confuse resistance with impedance or resistivity in a calculation or report.
- Report a measurement without its temperature and instrument conditions where they matter.
Only with a human decision
- Re-energising a circuit after a fault found by resistance testing.
May
- Measure resistance on circuits that are isolated and that the agent is authorized to test.
- Explain resistance, resistivity and impedance and how they differ.
Moral aspects Filled
- Faulty connections with high resistance start electrical fires in homes.
Who is affected
- Occupants of buildings
- Electricians and technicians
Owners Filled
Steward
Nobody owns the quantity; the owner of an installation answers for its condition.
Links to other meta-models Filled
parent
- Q107715 - registry parent class
- Q181175 - registry parent class
related
- physical quantity - a scalar quantity
- ohm - the SI unit
- Ohm law - voltage over current
- electrical impedance - for alternating current
What else AI and robots need to interact with it Filled
Identity and identifiers required Filled
- Vercy registry: vr.tr.electrical-resistance
- Wikidata: Q25358 (https://www.wikidata.org/wiki/Q25358)
- SI unit symbol: ohm omega symbol
- quantity symbol: R ISO 80000-6
Direct properties not applicable Not applicable
- unit: ohm V per A - SI derived unit
- copper resistivity: about 1.7 times 10 to the minus 8 ohm metre - at 20 degrees C
- temperature coefficient of copper: about 0.004 per degree C
Plane XCT: no invented physical properties.
Recognition optional Filled
- Voltage over current, in ohms
- Depends on material, geometry and temperature
- Impedance includes reactance; resistivity is per material
- Not visible; measured with an ohmmeter and marked on resistors by colour bands or codes.
Capabilities and actions required Filled
- explain resistance and Ohm law
- distinguish resistance, resistivity, impedance and conductance
- calculate resistance for circuits and conductors
- relay measurement methods
Hazards and failure modes required Filled
- Overheating from high resistance in connections
- Confusing resistance with impedance or resistivity
- Measurement errors from lead and contact resistance
Standards and interfaces required Filled
- SI Brochure from BIPM
- ISO 80000-6 electromagnetic quantities
- IEC standards for resistors and measurement
Context of use required Filled
- Not for anything; a property that governs current flow and is exploited in resistors and heaters.
- resistance of conductors and components
- resistivity of materials
- sheet resistance of thin films
- contact resistance
- impedance and characteristic impedance in AC circuits
- biological resistances such as transepithelial resistance
Sources Filled
- Wikidata item Q25358: electrical resistance - identity and sense of the item
- Wikipedia: Electrical resistance - general description of the item
Open questions
- Should impedance be a separate entry?
- How should material data be linked?
- The registry entry has merged aliases for impedance and biological resistances; should they be split off?
Machine files
Provenance
thing registry research (pass 2) · unreviewed
Built from: models/things/publications/thing-q25358/spec.json