A) unchanged
B) quarter of its earlier value
C) half of the earlier value
D) twice the earlier value
Correct Answer: A
Solution :
The strength of magnetic field at the observation point due to a straight current carrying wire is \[B=\frac{{{\mu }_{0}}i}{2\pi r}\]where r= distance of point from the wire. It is obvious from the relation that magnetic field does not depend on diameter of the wire, so it remains unchanged. NOTE: Since \[B\propto \frac{1}{r}\]. so B-r graph for an infinitely long straight wire is a rectangular hyperbola (as shown in figure).You need to login to perform this action.
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