Question

Identify which of the following is NOT a source of visible light?

• A. red-hot metal
• B. cool metal
• C. fluorescent bulb
• D. the Sun
• E. fire

Answer 1

The correct option is B cool metal

When the electrons in the atom are excited, for example by being heated, the additional energy pushes the electrons to higher energy orbits. When the electrons fall back down and leave the excited state, energy is re-emitted in the form of a photon.

Thus the hot objects release photons that have energies lying in the visible region. However photons from cool metal do not have energy enough to lie in visible region.