Source: https://guthlabs.ai/docs/instruments/magnetic-field-of-a-current-loop-solenoid-calculator/implementation/

instrument implementation / implementation-contract

# Magnetic Field of a Current Loop / Solenoid Calculator implementation

A source-bound implementation contract for Magnetic Field of a Current Loop / Solenoid Calculator; deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t5-197

**Effect**: Computation or source lookup only

## Input and validation requirements

The zero-radius input creates an undefined division-by-zero result that requires explicit rejection. The specification also leaves geometry-branch selection and current sign/unit conventions implicit, creating risks of silent wrong results.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "inputs": {
    "mode": "loop",
    "I": 2,
    "I_unit": "A",
    "R": 0.1,
    "R_unit": "m"
  },
  "expected_outputs": {
    "B": 0.000012566370614359173,
    "B_unit": "T"
  },
  "working": "B=μ0I/(2R)=(1.2566370614359173×10^-6 T·m/A×2 A)/(2×0.1 m)=(2.5132741228718346×10^-6)/(0.2)=1.2566370614359173×10^-5 T."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/magnetic-field-of-a-current-loop-solenoid-calculator/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/magnetic-field-of-a-current-loop-solenoid-calculator/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/magnetic-field-of-a-current-loop-solenoid-calculator/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche5/tranche5-results.json`