Q. A straight wire of diameter $0.5\ mm$ carrying a current of $1\ A$ is repaced by another wire of $1\ mm$ diameter carrying the same current. The strength of magnetic field far away is
A) Twice the earlier value
B) Half of the earlier value
C) Quarter of its earlier value
D) Unchanged
Explanation
(d) The magnetic field is given by $B = \frac{\mu_{0}}{4\pi}\frac{2i}{r}$
It is independent of the radius of the wire
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.