Two infinitely long wires carry currents $4 \mathrm{~A}$ and 3A placed along $X$-axis and $Y$-axis…
- $\frac{4 \mu_0}{2 \pi d}$
- $\frac{3 \mu_0}{2 \pi d}$
- $\frac{7 \mu_0}{2 \pi d}$
- $\frac{5 \mu_0}{2 \pi d}$
Solution

$ \Rightarrow \quad \mathbf{B}_y=\frac{\mu_0 \cdot 3}{2 \pi d} a \hat{\mathbf{i}} $ $\therefore$ Resultant magnetic field, $ \begin{aligned} B & =\sqrt{B_x^2+B_y^2} \\ & =\frac{\mu_0}{2 \pi d} \sqrt{4^2+3^2} \\ B & =\frac{5 \mu_0}{2 \pi d}\left(\text { at }-45^{\circ} \text { from } X \text {-axis }\right) \end{aligned} $
Asked in: AP EAMCET 2018 (22 Apr Shift 1)
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