A small compass is held horizontally and the centre of its needle is at the distance of 0.280 m directly north of the long wire that is perpendicular to the earth’s surface as in FIGURE 1. When there is no current in the wire, the compass needle points due north, which is the direction of the horizontal component of the earth’s magnetic field at the location. The component is parallel to the earth’s surface. When the current in the wire is 25.0 A, the needle points 230 east of north.

Question

A small compass is held horizontally and the centre of its needle is at the distance of 0.280 m directly north of the long wire that is perpendicular to the earth’s surface as in FIGURE 1. When there is no current in the wire, the compass needle points due north, which is the direction of the horizontal component of the earth’s magnetic field at the location. The component is parallel to the earth’s surface. When the current in the wire is 25.0 A, the needle points 230 east of north.
i) What is the possible diagram for the above condition?
ii) What is the magnitude of the horizontal component of the earth’s magnetic field at
the location of the compass?
iii) Explain what happen when current is increased
iv) Explain what happen when the current is reversed