Convert Square Millimeter (mm²) to Electron Cross Section (σₑ) instantly.
About these units
Square Millimeter (mm²)
A square millimeter represents the area of a square measuring 1 millimeter on each side. It is a tiny unit used extensively in engineering, electronics, material science, and medical instrumentation. Mechanical designers use mm² to determine cross-sectional areas of wires, beams, micro-mechanical parts, and precision components. In electronics, PCB traces, microchips, and sensors often specify dimensions in mm² for clarity and precision. Biomedical sciences also use mm² for cell colony measurements, tissue sample surfaces, and microscopic fields of view. Its size makes it ideal for quantifying structures too small for cm² but too large for micrometer-scale units.
Electron Cross Section (σₑ)
The electron cross section, often denoted σₑ, is not a fixed unit but rather a physical area representing the effective interaction size of an electron in scattering experiments. It is typically expressed in barns or submultiples such as square femtometers (fm²). Electron cross sections are vital in quantum electrodynamics (QED), X-ray scattering, atomic physics, and materials science. These values describe how electrons interact with photons, atoms, or other electrons, determining phenomena such as absorption, conductivity, and radiation shielding. Because electron interactions are probabilistic, σₑ provides a statistical measure of likelihood rather than a physical surface, illustrating how area units are used conceptually at quantum scales.