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23 units available
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To convert barns to m²: multiply by 10⁻²⁸. To fm²: multiply by 100.
1 b = 10⁻²⁸ m² = 100 fm². Millibarns (mb), microbarns (µb), and nanobarns (nb) are common submultiples.
For example, 1 Barn (b) = 1.973525e-25 Circular Inch (circ in).
| Barn (b) | Circular Inch (circ in) |
|---|---|
| 0.1 | 1.973525e-26 |
| 0.5 | 9.867626e-26 |
| 1 | 1.973525e-25 |
| 2 | 3.947050e-25 |
| 5 | 9.867626e-25 |
| 10 | 1.973525e-24 |
| 25 | 4.933813e-24 |
| 50 | 9.867626e-24 |
| 100 | 1.973525e-23 |
| 500 | 9.867626e-23 |
| 1000 | 1.973525e-22 |
The barn is a unit of area equal to 10⁻²⁸ m², used to express nuclear cross-sections — the effective target area of subatomic particles.
1 b = 10⁻²⁸ m² = 100 fm². Millibarns (mb), microbarns (µb), and nanobarns (nb) are common submultiples.
To convert barns to m²: multiply by 10⁻²⁸. To fm²: multiply by 100.
Quantifying nuclear reaction probabilities, neutron absorption, and particle scattering in reactor design.
The physicists named it 'barn' as a joke: nuclei were 'as big as a barn' compared to what they expected. Later units include 'outhouse' (10⁻⁶ barns) and 'shed' (10⁻²⁴ barns).
Thinking a barn is a large area — at the human scale 10⁻²⁸ m² is incomprehensibly small.
Cross-section = probability of interaction. A bigger barn value means a particle is more likely to 'hit the target' — hence the barn analogy.
The circular inch is the area of a circle one inch in diameter, equal to π/4 square inches (approximately 0.0005067 m²).
1 circular inch = π/4 in² ≈ 0.7854 in² ≈ 5.067 cm². Equals 1,000,000 circular mils.
To convert circular inches to in²: multiply by 0.7854. To cm²: multiply by 5.067.
Wire and cable cross-section calculations, especially for large conductors in power distribution.
The circular mil and circular inch exist solely to avoid π in cross-section math. Diameter² (in circular units) directly gives the area.
Confusing circular inch with square inch — a circular inch is about 78.5% of a square inch.
For a circle: area in circular inches = diameter². Area in square inches = diameter² × π/4. The circular unit absorbs the π/4 factor.



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