Question

A straight wire of diameter $0.5mm$ carrying a current of $1A$ is replaced by another wire of 1 mm diameter carrying the same current. How will this impact the strength of magnetic field far away ?

• A. Twice the earlier value
• B. Half of the earlier value
• C. Quarter of its earlier value
• D. Unchanged

Answer 1

The correct option is D Unchanged

Magnetic field at a point at a distance $x$ from a straight conductor carrying a current $I$ is given as:
$B=\frac{{\mu }_{0}I}{2\pi x}$
$\therefore$ B does not change with change in diameter of wire.