The effective mass of an electron in a crystal is derived from the band structure of the material. Mathematically, it is represented as: 1/m* = (1/ħ²) * (â²E/âk²) where m* is the effective mass, ħ is the reduced Planck's constant, E is the energy, and k is the wave vector. This equation highlights that the effective mass is inversely proportional to the curvature of the energy band.
