E=1. 55× 10−19 J.
ultraviolet light
When an electron drops from n = 2 to n = 1, it emits a photon of ultraviolet light. The step from the second energy level to the third is much smaller. It takes only 1.89 eV of energy for this jump. It takes even less energy to jump from the third energy level to the fourth, and even less from the fourth to the fifth.