The electron cross-section, often referred to as the electron scattering cross-section or simply the electron cross-section, is a term used in the fields of nuclear and particle physics to describe the likelihood of electrons interacting with other particles, such as atomic nuclei or other electrons, when they are subjected to various types of scattering experiments or interactions.
The electron cross-section is typically expressed in units of area, such as square meters (m²) or square femtometers (fm²), and it represents the effective target area presented by an electron for a particular type of interaction or scattering process. It is used to quantify the probability of electron interactions occurring in various experimental setups.
A square kilometer (often abbreviated as km²) is a unit of area in the International System of Units (SI). It represents a square with sides that each measure 1 kilometer in length.
One square kilometer is equal to 1,000,000 square meters (m²) because there are 1,000 meters in a kilometer, and when you square that length, you get 1,000 * 1,000 = 1,000,000 square meters.
To visualize the size of a square kilometer, you can imagine a square plot of land, each side of which measures 1 kilometer (approximately 0.621 miles). It's a commonly used unit to measure land area, particularly in countries that use the metric system.