The magnetic field at a distance r from a long wire carrying current i is 0.4 tesla. The magnetic field at a distance 2r is

Question

The magnetic field at a distance r from a long wire carrying current i is 0.4 tesla. The magnetic field at a distance 2r is (A) 0.2 tesla (B) 0.8 tesla (C) 0.1 tesla (D) 0.6 tesla

Tardigrade Admin · Accepted Answer

Magnetic field due to long wire, B=(μ0i/2π r) or B propto(1/r) When r is doubled, the magnetic field becomes half, i.e., now the magnetic field will be 0.2 T.

Q. The magnetic field at a distance $r$ from a long wire carrying current $i$ is $0.4$ tesla. The magnetic field at a distance $2 r$ is

0.2 tesla

0.8 tesla

0.1 tesla

0.6 tesla

Magnetic field due to long wire,
$B = \frac{μ _{0} i}{2 π r}$ or $B \propto \frac{1}{r}$
When $r$ is doubled, the magnetic field becomes half, i.e., now the magnetic field will be $0.2 T$ .

Q. The magnetic field at a distance r from a long wire carrying current i is 0.4 tesla. The magnetic field at a distance 2r is