Post office box

{
  "id": "MLC-T-IND-004437",
  "term": "Post office box",
  "field": "Industrial and trades",
  "definition": "A portable apparatus containing resistors, switches, and terminals arranged to function as a Wheatstone bridge for measuring electrical resistance. The name derives from its historical use by British General Post Office engineers for testing telegraph lines. The instrument includes multiple resistance coils, typically in decades of 1, 10, 100, and 1000 ohms, which are selected using plugs or dials to balance the bridge and determine the value of an unknown resistor.",
  "subject": "Electrical engineering",
  "translations": {
    "de": "Post Office Box",
    "es": "caja de correos",
    "fr": "boîte de P.O."
  },
  "url": "https://mlchart.com/terminology/industrial/post-office-box/"
}