A DC welding machine with a linear power source characteristic provides open circuit voltage of 80V and short circuit current of 800A. during welding with the machine, the measured arc current is 500A corresponding to an arc length of 5.0 mm and the measured arc current 460A corresponding to an arc length of 7.0 mm. the linear voltage (E) & arc length (L) characteristic of the welding arc can be given as (where E is in Volts and L is in mm)
(a) E = 20 + 2L (b) E = 20 + 8L
(c) E = 80 + 2L (d) E = 80 + 8L