Luminosity Distance Flux Cross-Scan - Observational Astrophysics: Distance, Flux, Transits, and Spectra Step by Step

Three exact rows show luminosity over distance square. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Flux divides luminosity by distance squared

The checked source keeps luminosity sixteen watts and distance four meters, so the distance square is sixteen and the flux is one.

F=\frac{16}{4^{2}}=\frac{16}{16}=1

Distance and luminosity pull flux in opposite ways

The first two rows hold luminosity fixed while distance doubles. The last row raises luminosity and distance together.

\begin{array}{c|c|c|c}L&d&d^{2}&F\\16&2&4&4\\16&4&16&1\\25&5&25&1\\\end{array}