Magnetic Effects & Magnetism

JEE Main level, numerical answer, medium

276 of 276

Question 276 of 276

Two parallel long current carrying wire separated by a distance 2r2 r are shown in the figure. The ratio of magnetic field at AA to the magnetic field produced at CC is x7\frac{x}{7}. The value of xx is _____

Show answer and solution

Answer: 5

BA=μ0i2πr+μ0(2i)2π(3r)=5μ0i6πrBC=μ0(2i)2πr+μ0i2π(3r)=7μ0i6πr∴BABC=57∴x=5\begin{aligned} & \mathrm{B}_{\mathrm{A}}=\frac{\mu_0 \mathrm{i}}{2 \pi \mathrm{r}}+\frac{\mu_0(2 \mathrm{i})}{2 \pi(3 \mathrm{r})}=\frac{5 \mu_0 \mathrm{i}}{6 \pi \mathrm{r}} \\ & \mathrm{B}_{\mathrm{C}}=\frac{\mu_0(2 \mathrm{i})}{2 \pi \mathrm{r}}+\frac{\mu_0 \mathrm{i}}{2 \pi(3 \mathrm{r})}=\frac{7 \mu_0 \mathrm{i}}{6 \pi \mathrm{r}} \\ & \therefore \frac{\mathrm{B}_{\mathrm{A}}}{\mathrm{B}_{\mathrm{C}}}=\frac{5}{7} \\ & \therefore \mathrm{x}=5\end{aligned}

JEE Main question paper PDF

Open a shift to read the full paper on this page, or download it.

JEE Main 2025 Apr 2 Shift 1 question paper

Open Download PDF

Opening paper…

Explain it as a whiteboard videoStep-by-step, in Hinglish or English. Your first video needs no login.Solved it on paper but got it wrong?Upload a photo of your working. Mistake Doctor marks the exact line that broke.

More Physics practice

JEE Main Physics practice question on Magnetic Effects & Magnetism (Biot-Savart’s Law and Ampere’s Circuital Law), with the answer and a step-by-step solution. Scan a question from your own book or paper to get a whiteboard video.