Question

Two long wires parallel to the page carry currents. Wire 1 = 1.5A and wire 2 = 1.1A and they are 1.8cm apart. Point P is 2.3 cm to the right of wire 2. What is the magnitude and direction of the magnetic field at P? A compass is placed at P, in which direction does the north needle point?

Answer 1

Solution :

The separation between the wires = d,

Separation between the 2nd wire and point P = r.

Also, all distances are converted from cm to m, to make all units S.I.

The north pole of the needle of campus kept at P will point towards PERPENDICULAR TO THE PAGE.

Reason : If we rotate a right hand screw clockwise (?), such that the motion of the screw will point towards the direction of current, then the tangent drawn along the rotation at point P will direct either into the page or out of the page, (depending on the direction of the current), both are perpendicular to the page.