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Question
The diagram below shows the top view of the Wire A shown by a cross (X), carrying current into the plane of the paper. Which of the compasses is correctly aligned with the magnetic field, produced by the current carrying wire?
Options
Only 1 is aligned.
Only 2 is aligned.
Both 1 and 2 are aligned.
Both 1 and 2 are not aligned.
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Solution
Only 1 is aligned.
Explanation:
A straight current-carrying wire generates circular magnetic field lines around it; thus, using the right-hand thumb rule, if the current is directed into the plane of the paper (shown by X), the magnetic field lines circulate in a clockwise direction.
A compass needle orients tangentially to the magnetic field lines, and at the position of compass 1, the field points to the right, indicating that compass 1 is aligned correctly.
At compass position 2, the magnetic field is expected to direct downward, but the compass indicates an upward orientation, indicating incorrect alignment.
Therefore, only compass 1 is aligned correctly.
