invalshoek

Invalshoek is a Dutch term used in physics and engineering that refers to the angle of incidence. It is defined as the angle between an incoming ray (such as light, sound, or radiation) and the normal to the surface at the point where the ray meets the surface. The normal is an imaginary line perpendicular to the surface. When the ray strikes the surface perpendicularly, the invalshoek is 0 degrees, and it increases toward 90 degrees as the ray becomes more grazing.

In optics, the invalshoek determines how much of the ray is reflected and how much is transmitted or refracted when crossing a boundary between media. The law of reflection states that the angle of incidence equals the angle of reflection, with both angles measured relative to the normal.

When light enters another medium, Snell's law governs refraction: n1*sin(theta1) = n2*sin(theta2), where theta1 is the invalshoek in the first medium and theta2 is the angle of the refracted ray in the second medium. The invalshoek affects focal quality, transmission losses, and glare.

Practically, the concept is used in designing solar panels to maximize incident radiation, in photography and astronomy to optimize illumination and imaging, and in radiography and acoustics to predict how waves propagate after hitting interfaces.

See also: angle of reflection, angle of refraction, Snell's law.