What must be the working voltage in Electrochemical machining? / » Unconventional Machine Process (UMP) solved MCQs / By admin Question: What must be the working voltage in Electrochemical machining? A. 10 v B. 20 v C. 30 v D. 40 v Answer» b. 20 v Note: The above multiple-choice question is for all general and Competitive Exams in India.