{
  "id": "quantities:electric-field-strength",
  "collection": "quantities",
  "slug": "electric-field-strength",
  "name": "Electric field strength",
  "summary": "Volts per metre, reported both for power-frequency electric fields near wiring and for radiofrequency fields near transmitters.",
  "status": "verified",
  "lastVerified": "2026-08-12",
  "data": {
    "aliases": [
      "E field",
      "V/m",
      "volts per meter"
    ],
    "quantityId": "electric-field-strength",
    "symbol": "E",
    "siUnit": "V/m",
    "units": [
      {
        "symbol": "kV/m",
        "name": "kilovolt per metre",
        "toBase": 1000
      },
      {
        "symbol": "V/m",
        "name": "volt per metre",
        "toBase": 1
      },
      {
        "symbol": "mV/m",
        "name": "millivolt per metre",
        "toBase": 0.001
      },
      {
        "symbol": "µV/m",
        "name": "microvolt per metre",
        "toBase": 0.000001
      }
    ],
    "measures": "Electric component of the field. At power frequency it is easily blocked by grounded conductive surfaces; at radiofrequency it is one of two interchangeable ways to express far-field exposure.",
    "conversions": [
      {
        "to": "power-density",
        "formula": "S (W/m²) = E² / 377",
        "note": "Valid in the far field of an antenna, where the wave impedance equals the impedance of free space, 376.73 Ω. Not valid within a wavelength of the source."
      },
      {
        "to": "electric-field-strength",
        "formula": "dBµV/m = 20 · log₁₀(E in µV/m)",
        "note": "Logarithmic form used by spectrum analysers and EMC test equipment."
      }
    ]
  },
  "sources": [
    {
      "id": "nist-si",
      "title": "The International System of Units (SI), NIST Special Publication 330",
      "publisher": "National Institute of Standards and Technology",
      "url": "https://www.nist.gov/pml/special-publication-330",
      "kind": "government",
      "retrieved": "2026-08-12"
    },
    {
      "id": "itu-fs-relations",
      "title": "Free-space path loss and power density relations (ITU-R P.525)",
      "publisher": "International Telecommunication Union",
      "url": "https://www.itu.int/rec/R-REC-P.525/en",
      "kind": "standard",
      "retrieved": "2026-08-12"
    },
    {
      "id": "fcc-1310",
      "title": "47 CFR § 1.1310 — Radiofrequency radiation exposure limits",
      "publisher": "U.S. Government Publishing Office (eCFR)",
      "url": "https://www.ecfr.gov/current/title-47/section-1.1310",
      "kind": "regulation",
      "retrieved": "2026-08-12"
    }
  ],
  "links": {
    "self": "https://emfbase.com/api/quantities/electric-field-strength",
    "html": "https://emfbase.com/quantities/electric-field-strength",
    "markdown": "https://emfbase.com/quantities/electric-field-strength.md",
    "collection": "https://emfbase.com/api/quantities"
  }
}