What is the observable indication when using fluorescent penetrants under UV light?

What is the observable indication when using fluorescent penetrants under UV light?

• A. Dark spots
• B. Fluorescent indications
• C. Color changes
• D. No visible changes

Answer: (B)

When you use fluorescent penetrants, the dye in the penetrant is excited by ultraviolet light and emits visible light. Defects on the surface trap the penetrant, and when illuminated, these areas glow brightly, producing a distinct fluorescent indication that you can see against a dark background. This bright glow specifically marks where flaws exist, which is why the observable indication is the fluorescent glow at defect sites. The other options don’t describe the signal produced by fluorescent penetrants under UV light.

When you use fluorescent penetrants, the dye in the penetrant is excited by ultraviolet light and emits visible light. Defects on the surface trap the penetrant, and when illuminated, these areas glow brightly, producing a distinct fluorescent indication that you can see against a dark background. This bright glow specifically marks where flaws exist, which is why the observable indication is the fluorescent glow at defect sites. The other options don’t describe the signal produced by fluorescent penetrants under UV light.