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Acceleration

In physics, acceleration is the rate of change of velocity over time. In one dimension, acceleration is the rate at which something speeds up or slows down. However, since velocity is a vector, acceleration describes the rate of change of both the magnitude and the direction of velocity. In international system of units, acceleration is measured in meters per second squared (m/s2).

In classical mechanics, for a body with constant mass, the acceleration of the body is proportional to the net force acting on it (Newton's second law):

where F is the resultant force acting on the body, m is the mass of the body, and a is its acceleration.

Abbe Number

In physics and optics is a measure of the material's dispersion (variation of refractive index with wavelength) in relation to the refractive index. The Abbe number V of a material is defined as:

Where nD, nF and nC are the refractive indices of the material at the wavelengths of the Fraunhofer lines D, F and C spectral lines (589.2 nm, 486.1 nm and 656.3 nm respectively). This formulation only applies to the visible spectrum.

Fraunhofer Lines  (Solar spectrum with Fraunhofer lines as it appears visually)

 

Abney Effect

The Abney effect describes the perceived hue shift that occurs when white light is added to a monochromatic light source.

(Animation showing how the white light afects the precived HUE from colors.)