Which statement about fluorescent materials is true?

• A. They emit light without any energy input.
• B. They absorb ultraviolet light and emit some energy as visible light.
• C. They emit only infrared light.
• D. They never appear to glow.

Answer: (B)

Fluorescent materials work by converting higher-energy light into lower-energy light. When exposed to ultraviolet light, their electrons get excited to a higher energy level. As they return to a lower level, they emit photons with lower energy, often in the visible range. This is why they glow under UV light. Some energy is lost as heat, which is why the emitted light is not the same energy as the absorbed UV.

The statement that they absorb ultraviolet light and emit some energy as visible light matches this behavior, so it’s the true description. The others don’t fit: emitting light without energy input would imply spontaneous glow, which isn’t how fluorescence works; emitting only infrared light isn’t the general outcome for fluorescent materials (they commonly emit visible light); and never appearing to glow contradicts the glowing effect fluorescence produces under excitation.