Déflexion

Déflexion is a term used in science to denote a deviation of a path, surface, or signal from a reference direction. It covers transverse displacement of a structure under load, angular deviation of a ray, or deflection of a particle’s trajectory. Magnitude is given as a deflection distance or a deflection angle.

In structural engineering, déflexion describes how a beam or plate moves under load. The transverse displacement w(x) depends on loading, geometry, and stiffness (modulus E and moment of inertia I). For a simply supported beam with a central load F, the maximum deflection is F L^3/(48 E I). Designers compare deflection to serviceability limits to ensure safety and proper function.

In optics and physics, déflexion refers to bending of light or particles by forces. Gravitational déflexion, predicted by general relativity and observed in gravitational lensing, bends light rays by tiny angles. Charged particles deflect in electric or magnetic fields, an effect exploited in spectrometers and accelerators.

In instrumentation and display technology, déflexion is the steering of an electron or ion beam by deflection plates or coils, as in cathode-ray tubes and oscilloscopes. The deflection sensitivity links input signals to beam displacement.

The term is widely used across disciplines to denote deviation from an intended path or form. Its precise meaning depends on context, but it is typically quantified by a deflection angle or a deflection distance.