{"schema":"https://ver.cy/schemas/card/1.0.0","id":"vr.tr.electrical-resistance","code":"thing-q25358","url":"https://ver.cy/models/thing/q25358/","name":"electrical resistance","alternateNames":["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"],"kind":"thing","status":"published","version":"0.2.0-wave.3","language":"en","classifiers":{"family":"Thing Registry","category":"Cross-cutting context","entryKind":"thing","plane":"XCT","domain":["XCT.QLT"],"industry":[],"navPath":"","tags":[],"facets":{}},"whatItIs":"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.","purpose":"Let an agent explain electrical resistance, its units, laws and measurement, distinguish resistance from resistivity, impedance and conductance, and support calculation and teaching.","scope":{"in":[],"out":[],"boundaries":[]},"distinguishingFeatures":["Ratio of voltage to current","Ohmic and non-ohmic behaviour","Temperature dependence","Scalar, unlike complex impedance"],"structure":{"bundles":[{"id":"concept","name":"Concept","description":"What resistance is.","layers":[{"id":"definition","name":"Definition","description":"Definition and law.","findings":[{"id":"definition-finding","name":"Definition","description":"Definition.","questions":[{"text":"What is electrical resistance, and what does Ohm law state and not state?","kind":"definition"},{"text":"Is the question about resistance, resistivity, impedance or conductance?","kind":"boundary"}]}]},{"id":"factors","name":"Factors","description":"What determines it.","findings":[{"id":"factors-finding","name":"Factors","description":"Factors.","questions":[{"text":"How do material, length, cross-section and temperature determine resistance?","kind":"definition"},{"text":"Which entry fits resistivity?","kind":"action"}]}]}]},{"id":"calculate","name":"Calculate","description":"Circuits and calculation.","layers":[{"id":"circuits","name":"Circuits","description":"Series and parallel.","findings":[{"id":"circuits-finding","name":"Circuits","description":"Circuits.","questions":[{"text":"How are resistances combined in series and parallel, and how is a circuit solved?","kind":"action"},{"text":"What is the result for the circuit in question?","kind":"measurement"}]}]},{"id":"power","name":"Power","description":"Power and heating.","findings":[{"id":"power-finding","name":"Power","description":"Power.","questions":[{"text":"How does resistance relate to power dissipation and heating?","kind":"definition"},{"text":"Which entry fits Joule heating?","kind":"action"}]}]}]},{"id":"measure","name":"Measure","description":"Measurement.","layers":[{"id":"methods","name":"Methods","description":"Methods.","findings":[{"id":"methods-finding","name":"Methods","description":"Methods.","questions":[{"text":"How is resistance measured, from ohmmeters to four-terminal sensing?","kind":"measurement"},{"text":"What accuracy and sources of error apply?","kind":"measurement"}]}]},{"id":"components","name":"Components","description":"Resistors.","findings":[{"id":"components-finding","name":"Components","description":"Components.","questions":[{"text":"How are resistors specified and marked?","kind":"provenance"},{"text":"Which entry fits resistors?","kind":"action"}]}]}]},{"id":"learn","name":"Learn","description":"Physics and teaching.","layers":[{"id":"physics","name":"Physics","description":"Microscopic origin.","findings":[{"id":"physics-finding","name":"Physics","description":"Physics.","questions":[{"text":"What is the microscopic origin of resistance, and what are superconductivity and non-ohmic behaviour?","kind":"provenance"},{"text":"Which entry fits superconductivity?","kind":"action"}]}]},{"id":"teach","name":"Teach","description":"Teaching.","findings":[{"id":"teach-finding","name":"Teach","description":"Teaching.","questions":[{"text":"How is resistance taught, and which misconceptions arise?","kind":"provenance"},{"text":"Which references are standard?","kind":"provenance"}]}]}]}]},"agentConduct":{"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."],"mustNot":["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."],"requiresHuman":["Re-energising a circuit after a fault found by resistance testing."]},"ethics":{"considerations":["Faulty connections with high resistance start electrical fires in homes."],"affectedParties":["Occupants of buildings","Electricians and technicians"]},"owners":{"steward":"Nobody owns the quantity; the owner of an installation answers for its condition.","roles":[],"masterSystems":[]},"relations":[{"target":"Q107715","type":"parent","note":"registry parent class"},{"target":"Q181175","type":"parent","note":"registry parent class"},{"target":"physical quantity","type":"related","note":"a scalar quantity"},{"target":"ohm","type":"related","note":"the SI unit"},{"target":"Ohm law","type":"related","note":"voltage over current"},{"target":"electrical impedance","type":"related","note":"for alternating current"}],"interaction":{"identity":{"applicability":"required","items":["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"]},"properties":{"applicability":"not-applicable","items":["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"]},"recognition":{"applicability":"optional","items":["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":{"applicability":"required","items":["explain resistance and Ohm law","distinguish resistance, resistivity, impedance and conductance","calculate resistance for circuits and conductors","relay measurement methods"]},"hazards":{"applicability":"required","items":["Overheating from high resistance in connections","Confusing resistance with impedance or resistivity","Measurement errors from lead and contact resistance"]},"interfaces":{"applicability":"required","items":["SI Brochure from BIPM","ISO 80000-6 electromagnetic quantities","IEC standards for resistors and measurement"]},"context":{"applicability":"required","items":["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":[{"title":"Wikidata item Q25358: electrical resistance","url":"https://www.wikidata.org/wiki/Q25358","note":"identity and sense of the item"},{"title":"Wikipedia: Electrical resistance","url":"https://en.wikipedia.org/wiki/Electrical_resistance","note":"general description of the item"}],"openQuestions":["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?"],"resources":{"spec":"/models/things/publications/thing-q25358/spec.json"},"provenance":{"origin":"thing registry research (pass 2)","builtFrom":["models/things/publications/thing-q25358/spec.json"],"providers":["Claude"],"researchStatus":"unreviewed","generatedAt":"2026-09-12T20:42:23Z","builder":"tools/build_cards.py@1.0.0"},"completeness":{"sections":{"classifiers":"filled","whatItIs":"filled","purpose":"filled","distinguishingFeatures":"filled","structure":"filled","agentConduct":"filled","ethics":"filled","owners":"filled","relations":"filled","interaction.identity":"filled","interaction.properties":"not-applicable","interaction.recognition":"filled","interaction.capabilities":"filled","interaction.hazards":"filled","interaction.interfaces":"filled","interaction.context":"filled","sources":"filled"},"notes":{"_gate":"Published through the thing publication gate 1.0 on 2026-10-06T19:51:57+00:00: completeness 1.00; sense: Wikidata description; 2 live sources; review by codex: pass","interaction.properties":"Plane XCT: no invented physical properties."},"score":1.0}}