Question

Curves in the graph shown give, as functions of radial distance $r$, the magnitude $B$ of the magnetic field inside and outside for long wires $\text{a}$, $\text{b}$, $\text{c}$ and $\text{d}$, carrying currents that are uniformly distributed across the cross-sections of the wires. The wires are far from one another. Which wire has the greatest radius ?

• A. $\text{a}$
• B. $\text{b}$
• C. $\text{c}$
• D. $\text{d}$

Answer 1

The correct option is C $\text{c}$

Magnetic field intensity $\left(\overrightarrow{B}\right)$ due to long solid cylindrical wire is shown in diagram


So, magnetic field due to cylindrical wire becomes maximum at the surface of wire i.e. $r=R$.

$\therefore$ wire $\text{c}$ has the greatest radius.

Therefore, option $\left(c\right)$ is the correct answer.