Question

1. the light from a sodium - vapor street lamp appears yellow. use the concept of energy levels to explain this phenomenon.

Explanation:

In a sodium - vapor lamp, sodium atoms are excited. When electrons in sodium atoms drop from higher energy levels to lower energy levels, they emit photons. The energy difference between these levels corresponds to photons in the yellow - light region of the electromagnetic spectrum.

Answer:

When electrons in sodium atoms in the sodium - vapor lamp transition from higher to lower energy levels, the emitted photons have energies corresponding to yellow light.