A student performs an experiment to study the magnetic effect of current around a current carrying straight conductor. He reports that:
(i) the direction of deflection of the north pole of a compass needle kept at the given point near the conductor remains unaffected even when the terminals of the battery sending current in the wire are interchanged.
(ii) for a given battery, the degree of deflection of a N-pole decreases when the compass
is kept at a point farther away from the conductor. Which of the above observations of the student in incorrect and why?
(i) The first statement is incorrect, because the direction of the magnetic field around
the conductor is reversed when the direction of the current flowing in the conductor changes. Hence, the direction of deflection of N-pole of the compass needle cannot remain unaffected when the terminals of the battery sending current in the wire or conductor are interchanged.
(ii) The second statement is correct because the magnetic field decreases with the increases in the distance from the conductor.