question_answer

Two thin metallic strips, carrying current in the direction   shown,   cross   each   other perpendicularly without touching but being close to each other, as shown in the figure. The regions which contain some points of zero magnetic induction are:

A)  I and II        

B)  I and III

C)  I and IV        

D)  II and III

Correct Answer: C

Solution :

Magnetic field due to both currents at each point on line CD being equal and opposite  cancel while at each point on line AB they are added up.       Hence, magnetic induction in regions I and IV will be zero.