Deflexionswinkel

Deflexionswinkel, in physics often called the deflection angle, denotes the angle by which an initially straight trajectory is rotated as a result of an interaction with a field, potential, or boundary. It is typically denoted by θ or α and measured as the angle between the initial direction of motion and the final direction after the interaction. The concept is used across several disciplines, including particle physics, optics, and astrophysics.

In scattering theory, the deflection angle is a function of the impact parameter b for a central potential. For a given b, the trajectory is deflected by θ(b). The differential cross section is related by dσ/dΩ = (b / sin θ) |db/dθ|. In Rutherford scattering, the angle characterizes the extent of deflection produced by the Coulomb potential, linking microscopic interactions to observable angular distributions.

In charged-particle beam optics, the deflection angle produced by a magnetic field is determined by the bend radius R = p/(qB) and the length of the field region, with θ ≈ L/R = qBL/p for a uniform field. Deflection is a fundamental principle for steering beams in accelerators and spectrometers.

In optics, the deflection angle describes the change of direction of a light beam at interfaces or through media. Using Snell's law, the relation between the incident angle i and the refracted angle r determines the deviation δ = i − r (or, more generally, the angle between incident and emergent rays, depending on convention).

In gravitational physics, light deflection by mass follows general relativity. For a point mass M and impact parameter b in the weak-field limit, the deflection angle is α̂ = 4GM/(c^2 b). This underpins gravitational lensing phenomena observed in astronomy.

Deflexionswinkel is expressed in radians or degrees, with radians common in theoretical work, and serves as a basic observable linking dynamics, geometry, and interactions.