High ultraviolet radiation emissions from GMAW can cause atmospheric oxygen in the vicinity of the arc to convert to:

High ultraviolet radiation emissions from GMAW can cause atmospheric oxygen in the vicinity of the arc to convert to:

• A. Ozone
• B. Carbon monoxide
• C. Argon
• D. Carbon dioxide

Answer: (A)

Ultraviolet radiation from the welding arc provides energy that breaks oxygen molecules in the surrounding air. Once the O2 is split, the free oxygen atoms readily combine with O2 to form ozone (O3). The basic steps are O2 + hv -> 2O and then O + O2 + M -> O3 + M. This ozone formation happens in the bright, UV-rich zone near the arc, where oxygen is present. The other options don’t fit because carbon monoxide and carbon dioxide form from burning carbon-containing materials, and argon is an inert shielding gas, not produced by UV-driven oxygen chemistry.

Ultraviolet radiation from the welding arc provides energy that breaks oxygen molecules in the surrounding air. Once the O2 is split, the free oxygen atoms readily combine with O2 to form ozone (O3). The basic steps are O2 + hv -> 2O and then O + O2 + M -> O3 + M. This ozone formation happens in the bright, UV-rich zone near the arc, where oxygen is present. The other options don’t fit because carbon monoxide and carbon dioxide form from burning carbon-containing materials, and argon is an inert shielding gas, not produced by UV-driven oxygen chemistry.