Source: https://guthlabs.ai/docs/instruments/electric-field-from-point-charge-s-calculator/

instrument / verified-clean

# Electric Field from Point Charge(s) Calculator

The current ledger marks this instrument verified clean within the source-bound verification corpus.

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Inspectable records

[01**Overview**Purpose and lifecycle](<https://guthlabs.ai/docs/instruments/electric-field-from-point-charge-s-calculator/>)[02**Mechanism**Method and assumptions](<https://guthlabs.ai/docs/instruments/electric-field-from-point-charge-s-calculator/mechanism/>)[03**Implementation**Binding and validation](<https://guthlabs.ai/docs/instruments/electric-field-from-point-charge-s-calculator/implementation/>)[04**Qualification**Evidence and errata](<https://guthlabs.ai/docs/instruments/electric-field-from-point-charge-s-calculator/qualification/>)

## Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

**Area**: Physics — Kinematics/Projectiles/Orbits, Forces/Energy/Momentum, Rotational Dynamics, Gravitation, Oscillations/Waves, Optics, E&M Fields, Relativity, Quantum, Statistical Thermo

**Tranche**: tranche-5

**Evidence ID**: t5-174

**Ledger rows**: 1

No ledger note is attached.

## Review findings

The honest-label point-charge idealization is appropriate, but the label should also disclose the assumed dimensionality and the singular behavior at charge locations. Verdict is NEEDS_REVIEW because the exact position dimensionality and input/output unit conventions are ambiguous, and the stated formula is incomplete for the requested vector output.

### Formula and scope findings

- E=kq/r² is a scalar-magnitude formula, not a complete vector formula. For a charge at position r_i and field point r, the vector formula is E_i=k q_i (r-r_i)/|r-r_i|³.

- Multiple-charge computation must explicitly be E_total=Σ_i E_i, with the signed charge q_i determining direction.

- The specification does not define the value or units of k; the standard vacuum value is approximately 8.98755×10^9 N·m²/C².

### Unit assumptions

- Charges are supplied in coulombs after conversion from prefixes such as μC or nC.

- Positions and distances are in metres; the field point and charge positions use the same Cartesian coordinate system.

- The 2D canvas is treated as the z=0 plane in 3D space.

- Electric-field outputs are in N/C, equivalent to V/m.

- Test calculations use k=8.98755×10^9 N·m²/C².

## Boundary hardening

**BREAK_CLAIMED** · SELF_FLAGGED

A nonzero point charge at the field point makes r² = 0, so the electric field is undefined. The calculator must reject coincident charge and field-point inputs rather than produce a numeric result.

## Errata and corrections

No applied erratum is attached to this unique-name record.

## Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

````
{
  "inputs": {
    "charges": [
      {
        "q": "2 μC",
        "position_m": [
          0,
          0
        ]
      }
    ],
    "field_point_m": [
      3,
      4
    ],
    "k_N_m2_per_C2": 8987550000
  },
  "expected_outputs": {
    "E_vector_N_per_C": [
      431.4024,
      575.2032
    ],
    "E_magnitude_N_per_C": 719.004,
    "direction_unit_vector": [
      0.6,
      0.8
    ]
  },
  "working": "Displacement=(3−0,4−0)=(3,4) m. r=√(3²+4²)=5 m. q=2 μC=2×10⁻⁶ C. E=kq/r²=(8.98755×10⁹)(2×10⁻⁶)/25=17,975.1/25=719.004 N/C. Direction=(3/5,4/5)=(0.6,0.8). Vector E=719.004(0.6,0.8)=(431.4024,575.2032) N/C."
}
````

## Related workflows

No source-defined multi-instrument workflow membership is recorded.

## Sources and evidence

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

- `VERIFIED_LEDGER.json · VERIFIED_CLEAN`

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

- `BOUNDARY_HAZARD_CATALOG.json`