Answer
Potential Difference = 6 A
Work Step by Step
emf = 20
internal resistance = 4
external resistance = 4
3(emf - internal resistance)- (2)(i)(external resistance) = 0
i = 3emf /( 3(internal resistance) + 3(external resistance))
i = 3(20)/(3(4) + 2(4))
i = 60/20
i = 3
you multiply i by 2 to account for both.
Potential difference = 2i = 2(3) = 6
