What is the effect of reverse polarity (DC positive)?

• A. Deeper penetration
• B. Shallower penetration
• C. No change
• D. Varies

Answer: (A)

Where the arc’s heat goes determines how deep the weld will penetrate. With DC positive at the electrode (reverse polarity), more heat is directed into the base metal, causing the weld pool to melt deeper into the parent material and produce deeper penetration. If you were using straight polarity (electrode negative), the heat tends to stay more with the electrode, resulting in shallower penetration. This is why reverse polarity is commonly chosen when greater root depth is needed, especially on thicker sections.