question_answer 21)

The wires whichconnect the battery of an automobile to its starting motor carry a current of 300 A (for a short time). What is the force per unit length between the wires if they are 70 cm long and 1.5 cm apart? Is the force attractive or repulsive? 

Answer:

Using,                                                  Since the currents in two wires are in opposite direction so the force is repulsive.