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

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 $2 r$ is\

Professor PC Thomas Classes · Answer

(a) : $B=\frac{\mu_{0} i}{2 \pi r}$ or $B \propto \frac{1}{r}$ When $r$ is doubled, the magnetic field becomes halved i.e.,now the magnetic field will be 0.2 T .\