When a promoted electron falls back to the lower energy level, what does it do?

• A. Releases a proton
• B. Emits a photon
• C. Becomes a proton
• D. Rises to higher energy states

Answer: (B)

When an electron in an atom is promoted to a higher energy level and then falls back, the energy it loses is released as light. The emitted light is carried by a photon whose energy matches the difference between the two energy levels, so E = hν (or E = hc/λ). If the electron doesn’t drop in one step, it can cascade through intermediate levels and emit multiple photons, each with a smaller energy corresponding to the successive gaps. This is why excited atoms glow and produce specific spectral lines. The other possibilities—releasing a proton, becoming a proton, or rising to higher energy states—don’t describe electronic transitions; they involve nuclear changes or require energy input, not emission.