What is the purpose of the inner phosphor coating of the fluorescent tube as shown in figure "A" of the illustration? EL-0081

Correct Answer: Option B — absorb invisible ultraviolet light and emit visible white light

Fluorescent tubes rely on mercury vapor discharges that emit invisible ultraviolet radiation. The internal phosphor coating absorbs this short-wave UV energy and fluoresces, effectively converting it into visible white light suitable for marine compartment illumination.