Question

A long straight wire along z axis carries a current I in the negative z direction. The magnetic vector $\overrightarrow{B}$ at a point having coordinates (x, y) in the z = 0 plane is

• A. $\frac{\mu_0I}{2\pi}$$\,\frac{(y_i-x_j)}{(x^2-y^2)}$
• B. $\frac{\mu_0I}{2\pi}$$\,\frac{(x\hat{i}+y\hat{j})}{(x^2+y^2)}$
• C. $\frac{\mu_0I}{2\pi}$$\,\frac{(x_i-y_j)}{(x^2+y^2)}$
• D. $\frac{\mu_0I}{2\pi}$$\{\frac{x\hat{i}+y\hat{j}}{x^2+y^2}\}$

Answer 1

Answer: (A)

Here, current flows in the long straight wire along $-ve \,z$ direction. So magnetic field B lies in $(x, y)$ plane