Absorption Uses the Same Gap in Reverse - Atomic Spectra: Energy Levels and Line Series Step by Step

Absorption records the opposite direction with the same gap. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Absorption uses the same two energies

Changing the direction to absorption does not change the gap value.

E_{upper} - E_{lower}=9 - 4=5\ \mathrm{J}

The photon direction changes, not the arithmetic

The accepted gap is still 5 joules, with direction recorded as absorption.

\Delta E=5\ \mathrm{J}