{
  "id": "glossary:inverse-square-law",
  "collection": "glossary",
  "slug": "inverse-square-law",
  "name": "Inverse-square law",
  "summary": "In the far field, doubling the distance quarters the power density: the cheapest and most reliable mitigation available.",
  "status": "verified",
  "lastVerified": "2026-08-12",
  "data": {
    "definition": "Power density from a point source falls as 1/d². Three times the distance is nine times less; ten times the distance is a hundred times less. This is why moving a router across a room outperforms most shielding purchases. Two caveats: it does not apply in the near field, and it does not apply to fields from extended sources such as a long transmission line, where fall-off is closer to 1/d.",
    "category": "physics",
    "seeAlso": [
      "quantities:power-density",
      "emitters:wifi-router"
    ]
  },
  "sources": [
    {
      "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"
    }
  ],
  "links": {
    "self": "https://emfbase.com/api/glossary/inverse-square-law",
    "html": "https://emfbase.com/glossary/inverse-square-law",
    "markdown": "https://emfbase.com/glossary/inverse-square-law.md",
    "collection": "https://emfbase.com/api/glossary"
  }
}