Why should you clean the contacts on a plug or jack?

• A. To reduce resistance by loosening contact surfaces
• B. To maintain good electrical contact and prevent high resistance or intermittent connections
• C. To remove lubricant from contacts
• D. To adjust impedance for better signal transfer

Answer: (B)

Keeping contacts clean ensures a solid metal-to-metal path for current. Dirt, oxidation, and moisture on plug or jack surfaces act like a barrier, raising contact resistance and making connections unstable. That’s why the main goal of cleaning is to maintain good electrical contact and prevent high resistance or intermittent connections. The other ideas aren’t what cleaning achieves: you don’t want to loosen contact surfaces, removing lubricants isn’t the primary purpose (and many contacts aren’t lubricated), and cleaning doesn’t adjust impedance.