JAMB Physics 1983 Question 33

Question 33

Magnetism

Each of the diagrams in Fig. 6 represents two current carrying conductors situated close to each other. In which two diagrams are the forces between the two wires attractive?

A.I and V
B.I and III
C.II and IV
D.II and V
E.III and IV.

Show the answer and explanation

Answer: B (I and III)

Explanation

Parallel wires attract when their currents flow in the same direction. In I both currents go to the right and in III both go to the left; in II and IV they are opposite (repel), and in V the wires are at right angles.