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Equation 6 · Part 8 · How Scientific Instruments and Metrology Actually Work

Denominator: nsinα

d  ≈  0.61 λnsin⁡αd \;\approx\; \frac{0.61\,\lambda}{n\sin\alpha}
nsin⁡αn\sin\alpha

What this part means

The complete quantity below the fraction bar; it must be nonzero for this division.

Its job in the formula

nsinα occurs below the fraction bar. The quantity above the bar is divided by this expression; zero is excluded as a denominator.

The passage around this formula

…system with a circular aperture is bounded, in the simplest diffraction-limited approximation, by a form of the Rayleigh criterion: d  ≈  0.61 λnsin⁡αd \;\approx\; \frac{0.61\,\lambda}{n\sin\alpha}. where λ\lambda is the wavelength of the illuminating radiation, and nsin⁡\sinα\alpha is the numerical aperture of the imaging system. For visible light this caps optical microscopy at roughly 200 nanometres — far too coarse to resolve individual atoms, whose spacing in a solid is typically a few tenths of a nanometre. Electron microscopy exploits the far shorter de…

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Learn the underlying idea

A fraction a/b means a divided by b. The top number is the numerator; the bottom number is the denominator, and it cannot be zero.

Open the illustrated fractions: division written vertically guide →

Sources cited in the article section

These citations provide research context; check each source for the exact claim it supports.