CBSE Class 10 Science 2019 · Paper 31/4/2 · Question 12

Drawing: Copy the two conductors with the current flowing downwards in both. Round each conductor draw concentric circular field lines in planes perpendicular to it (drawn as rings round the conductor). By the right-hand thumb rule, with the thumb pointing down along the current, the lines go round clockwise when seen from above; so between the conductors the field lines of the left conductor come out of the page and those of the right conductor go into it. Magnitude of the magnetic field at X: Zero. Justification: X is at the same distance from two conductors carrying the same current, so the magnetic fields of the two conductors at X are equal in magnitude. As the currents are in the same direction, the two fields at X, a point between the conductors, are in opposite directions. Equal and opposite fields cancel, so the net magnetic field at X is zero ($B_X=0$); X is a neutral point.