Red Seal Electrician Practice
Wiring and componentsQuestion 3 of 1506

Which statement about a mercury-wetted switch contact is correct?

  1. It handles very high current and keeps contacts from bouncing
  2. It limits bounce, but only on low-current contacts
  3. It only works on DC circuits and fails to carry any current on AC circuits
  4. It increases the bounce slightly, but it lowers the contact resistance a great deal
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Correct answer: It limits bounce, but only on low-current contacts

Mercury wetting keeps the circuit continuous during bounce, but it suits low-ampacity contacts only.

Source: Lessons in Electric Circuits IV: Digital (Kuphaldt), 4.4: Contact “Bounce”

Practice wiring and components

Questions last reviewed: 18 October 2026