Q 43. Two pipes of inner diameter 100 mm and outer diameter 110 mm each are joined by flash – butt welding using 30 V power supply. At the interface, 1 mm of material melts from each pipe which has a resistance of 42.4 Ω. If the unit melt energy is 
, then time required for welding (in s) is
(A) 1
(B) 5
(C) 10
(D) 20
Answer: (C)
Explanation:
