Two Straight Rods 60 Cm Long and 2

Multiple Choice

Two straight rods 60 cm long and 2.0 mm apart in a current balance carry currents of 18 A each in opposite directions.What mass must be placed on the upper rod to balance the magnetic force of repulsion?

A) 0.50 g
B) 0.99 g
C) 9.7 g
D) 4.3 g
E) 1.6 g