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Optics

Field: Optics

Sequence of Expressions

The ratio of the sines of the angles of incidence and refraction is equivalent to the ratio of phase velocities in the two media, or equivalent to the reciprocal of the ratio of the indices of refraction: n1sin⁡θ1=n2sin⁡θ2n_1 \sin \theta_1 = n_2 \sin \theta_2.
On a smooth boundary, the angle of reflection equals the angle of incidence, and the incident ray, reflected ray, and normal to the surface all lie in the same plane.
The intensity of plane-polarized light that passes through an analyzer varies as the square of the cosine of the angle between the plane of the polarizer and the transmission axes of the analyzer: I=I0cos⁡2θI = I_0 \cos^2 \theta.
The maximum polarization of a ray of light may be achieved by letting the ray fall on a surface of a transparent medium in such a way that the refracted ray makes an angle of 90∘90^\circ with the reflected ray: tan⁡θB=n2n1\tan \theta_B = \frac{n_2}{n_1}.
The absorbance of a material sample is directly proportional to its thickness and the concentration of the attenuating species: A=ϵlcA = \epsilon l c.
The intensity of scattered light is inversely proportional to the fourth power of the wavelength: I∝1λ4I \propto \frac{1}{\lambda^4}.
The total luminance of a light source composed of several monochromatic lights is equal to the sum of the luminances of the individual components.
If a point of the retina is excited by a light which undergoes periodic variations, and if the period is sufficiently short, a continuous sensation results that is equal to the mean of the light intensity.
The path taken between two points by a ray of light is the path that can be traversed in the least time.
Every point on a wavefront is itself the source of spherical wavelets, and the secondary wavelets emanating from different points mutually interfere.
The radiant intensity or luminous intensity observed from an ideal diffusely reflecting surface or ideal diffuse radiator is directly proportional to the cosine of the angle θ\theta between the direction of the incident light and the surface normal.