Question

How will doubling the current through a wire affect the magnetic field due to the wire at a distance $1m$ directly above the wire?

• A. The direction of the magnetic field will curve sharper.
• B. The magnetic field strength will double.
• C. The direction of the magnetic field will reverse.
• D. The magnetic field strength will quadruple.

Answer 1

Answer: (B)

The magnetic field strength will double.

Magnetic field at a distance d from a straight wire $B=\frac{{\mu }_{o}I}{2\pi d}$

$⟹$ $B\propto I$

Thus doubling the current in the wire will also double the strength of magnetic field at that point.

Hence option B is correct.