Question

How will the magnetic field of a straight wire carrying a constant current interact with the needle of a compass? Does the interaction depend on the relative orientation of the wire and the compass needle? Does the interaction depend on the location of the needle relative to the wire? Does the interaction depend on the distance between the wire and the needle?

Answer 1

Answer:

the needle will direct its North South according to the magnetic field of current carrying wire.

Explanation:

A current carrying wire always has a magnetic field around it, in circular loops. This magnetic field will be either clockwise or anticlockwise depending on the direction of current.

Right hand rule tells the direction. Place the current carrying wire in your right hand with thumb pointing the direction of current. Curl of the fingers tell the direction of current.

When the needle gets in the vicinity of the field, its poles aligns itself with the field. (previous position of the compass needle has no effect on its position in the field). The north pole and south pole will be set in the direction of magnetic field.

The distance between the needle and wire does effect the strength (accuracy) of the needle position. Strong field will create strong deflection of the needle whereas when the distance from wire increases, field weakens, thus the deflection of needle will be weak.