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In the differential form formulation on arbitrary space times, F = 1 / 2 F αβ dx α ∧ dx β is the electromagnetic tensor considered as a 2-form, A = A α dx α is the potential 1-form, = is the current 3-form, d is the exterior derivative, and is the Hodge star on forms defined (up to its orientation, i.e. its sign) by the ...
German astronomer Johannes Kepler discussed the inverse-square law and how it affects the intensity of light. In proposition 9 of Book 1 in his book Ad Vitellionem paralipomena, quibus astronomiae pars optica traditur (1604), the astronomer Johannes Kepler argued that the spreading of light from a point source obeys an inverse square law: [15] [16]
It was derived by Johannes Kepler in 1609 in Chapter 60 of his Astronomia nova, [1] [2] and in book V of his Epitome of Copernican Astronomy (1621) Kepler proposed an iterative solution to the equation. [3] [4] This equation and its solution, however, first appeared in a 9th-century work by Habash al-Hasib al-Marwazi, which dealt with problems ...
For common glass (n 2 ≈ 1.5) surrounded by air (n 1 = 1), the power reflectance at normal incidence can be seen to be about 4%, or 8% accounting for both sides of a glass pane. Brewster's angle [ edit ]
Ed Sheeran has apologised to Ruben Amorim after gatecrashing a Sky Sports interview with the new Manchester United manager.. Amorim was speaking to presenter Kelly Cates as well as pundits Roy ...
Image credits: borez #2. 2008: I came down with swine flu and had to wear a surgical mask. My deadbeat dad went to jail. And on Christmas morning I found my beloved pet parakeet dead on the bottom ...
This article is part of The D.C. Brief, TIME’s politics newsletter. Sign up here to get stories like this sent to your inbox. Publicly, Joe Biden never wavered. Privately, those close to him ...
As a pencil of light goes through a flat plane of glass, its half-angle changes to θ 2. Due to Snell's law, the numerical aperture remains the same: NA = n 1 sin θ 1 = n 2 sin θ 2. In optics, the numerical aperture (NA) of an optical system is a dimensionless number that characterizes the range of angles over which the system can accept or ...