Q. 35.0( 1 Vote )
A long, straight wire carries a current along the z-axis. One can find two points in the x-y plane such that
A. the magnetic fields are equal
B. the directions of the magnetic fields are the same
C. the magnitudes of the magnetic fields are equal
D. the field at one point is opposite to that at the other point.
When a current carrying wire is along z-axis, the magnetic field can be found using right hand thumb rule.
Here X represents the field is going in and O represents field is coming out.
First case, if two points in the XY plain are above the wire and at same distance from z-axis, then both will lie in the X region(field going in), thus have same direction of magnetic field and magnitudes of magnetic field would be same.
Second case , if the two points in XY plane are at same distance from z axis but one point is above the wire and one is below it, then the direction of the electric field would be opposite for both the points. One point having X direction (going in) and other having O direction (coming out).
First two cases satisfy options (B),(C) and (D).
Thus, options (B),(C) and (D) are the correct options.
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