Convert Picometer (pm) to Long Reed (long reed) instantly.
About these units
Picometer (pm)
At 10⁻¹² meters, the picometer occupies a scale close to the dimensions of atoms but slightly finer than typical atomic radii. Chemists use picometers to express covalent bond lengths, ionic radii, and atomic radii. For example, the radius of a hydrogen atom is about 53 pm. The unit also appears frequently in crystallography, where X-ray diffraction reveals lattice spacing on the order of a few hundred picometers. The picometer provides a numeric convenience: atomic structures are neither too large nor too small to measure accurately in this unit. In physics, picometer-scale distances become relevant when examining the interactions of electrons in tightly bound orbitals or in high-resolution measurements of electric dipole moments. It is a unit that bridges atomic size with the precision of modern measurement tools.
Long Reed (long reed)
The long reed is a traditional unit of length used in Egypt and other ancient cultures, roughly equivalent to 2 cubits. It was employed in surveying, architecture, and the measurement of agricultural fields. The unit's length made it suitable for laying out longer distances with relatively few measurements, especially in river valley contexts where precision at large scales was important for irrigation and crop management. Historical records show the long reed in use for temple construction, pyramidal measurements, and land division, illustrating the practical integration of human-based units into early engineering practices.