Physics

Convert illuminance between lux and foot-candles with rounding controls and plain or scientific display. Includes a quick reference table.

Use Malus’s law to find transmitted intensity, percent transmitted, or the angle between polarizers. Includes non-ideal polarizer options.

Solve for object distance, image distance, or focal length. Includes magnification, image type, and a Beginner vs Physics sign check.

Convert between optical density (OD), absorbance, transmittance (T), %T, and intensity ratio. Optional Beer-Lambert concentration step.

Estimate radar line-of-sight horizon from antenna height. Include k-factor refraction, target height, and optional clutter. Output km, mi, or nmi.

Solve for a missing refraction angle or refractive index with Snell’s law. Includes normal vs surface angle help, TIR check, and critical angle.

Calculate diffraction-limited angular resolution from aperture and wavelength. Compare Rayleigh, Dawes, Sparrow, and convert to arcsec or detail size.

Calculate circular aperture area from diameter or from focal length and f-number. Convert units and compare light-gathering ratios and stops.

Estimate distance using a mil or MOA reticle. Use target size or the horizon method, plus optional SFP magnification correction.

Compute Planck spectral radiance (per wavelength or frequency), peak location, and total power using temperature, emissivity, and area.