{"record":{"id":"3a6b7194d3fd2919","repo":"TheAlgorithms/Python","slug":"hole-concentration-cannot-be-negative-in-a-semicon","errorCode":null,"errorMessage":"Hole concentration cannot be negative in a semiconductor","messagePattern":"Hole concentration cannot be negative in a semiconductor","errorType":"validation","errorClass":"ValueError","httpStatus":null,"severity":"error","filePath":"electronics/carrier_concentration.py","lineNumber":48,"sourceCode":"    >>> carrier_concentration(electron_conc=-1000, hole_conc=0, intrinsic_conc=1200)\n    Traceback (most recent call last):\n        ...\n    ValueError: Electron concentration cannot be negative in a semiconductor\n    >>> carrier_concentration(electron_conc=0, hole_conc=-400, intrinsic_conc=1200)\n    Traceback (most recent call last):\n        ...\n    ValueError: Hole concentration cannot be negative in a semiconductor\n    >>> carrier_concentration(electron_conc=0, hole_conc=400, intrinsic_conc=-1200)\n    Traceback (most recent call last):\n        ...\n    ValueError: Intrinsic concentration cannot be negative in a semiconductor\n    \"\"\"\n    if (electron_conc, hole_conc, intrinsic_conc).count(0) != 1:\n        raise ValueError(\"You cannot supply more or less than 2 values\")\n    elif electron_conc < 0:\n        raise ValueError(\"Electron concentration cannot be negative in a semiconductor\")\n    elif hole_conc < 0:\n        raise ValueError(\"Hole concentration cannot be negative in a semiconductor\")\n    elif intrinsic_conc < 0:\n        raise ValueError(\n            \"Intrinsic concentration cannot be negative in a semiconductor\"\n        )\n    elif electron_conc == 0:\n        return (\n            \"electron_conc\",\n            intrinsic_conc**2 / hole_conc,\n        )\n    elif hole_conc == 0:\n        return (\n            \"hole_conc\",\n            intrinsic_conc**2 / electron_conc,\n        )\n    elif intrinsic_conc == 0:\n        return (\n            \"intrinsic_conc\",\n            (electron_conc * hole_conc) ** 0.5,","sourceCodeStart":30,"sourceCodeEnd":66,"githubUrl":"https://github.com/TheAlgorithms/Python/blob/f5988cc09713315817df6a7e327e258013a94440/electronics/carrier_concentration.py#L30-L66","documentation":"Thrown by carrier_concentration() when hole_conc < 0 while exactly one argument is 0. Hole concentration is a physical count per volume and cannot be negative, so the library rejects it before computing the mass-action-law result.","triggerScenarios":"carrier_concentration(electron_conc=0, hole_conc=-400, intrinsic_conc=1200) — exactly one zero (electron_conc) but hole_conc is negative.","commonSituations":"Sign flips when computing p = ni^2/n manually and passing the wrong operand order; negative noise in measured data; spreadsheet columns with stray negative formatting.","solutions":["Correct the sign of hole_conc; valid inputs are non-negative.","Validate measured data before the call and reject/clamp physically impossible negatives at ingestion.","If you meant 'unknown', pass 0 for hole_conc instead of a negative placeholder."],"exampleFix":"# before\ncarrier_concentration(electron_conc=0, hole_conc=-400, intrinsic_conc=1200)\n\n# after\ncarrier_concentration(electron_conc=0, hole_conc=400, intrinsic_conc=1200)","handlingStrategy":"validation","validationCode":"if hole_conc < 0:\n    raise ValueError(\"hole_conc must be >= 0\")\nresult = carrier_concentration(electron_conc, hole_conc, intrinsic_conc)","typeGuard":null,"tryCatchPattern":null,"preventionTips":["Check operand order when deriving p = ni^2/n yourself.","Use 0 (not a negative number) to mark an unknown."],"tags":["electronics","semiconductor","physics","validation","sign-error"],"backgroundTag":null,"analyzedSha":"f5988cc09713315817df6a7e327e258013a94440","analyzedAt":"2026-08-14T17:30:07.041Z","schemaVersion":2},"datasetVersion":"2026-08-15T22:17:37.221Z"}