Moving Charges and Magnetism - Result Question 48
49. The magnetic field $(d \vec{B})$ due to a small element $(d \ell)$ at a distance $(\vec{r})$ and element carrying current $i$ is
[1996] (a) $d \vec{B}=\frac{\mu_0}{4 \pi} i(\frac{\overrightarrow{{}d \ell} \times \vec{r}}{r})$
(b) $d \vec{B}=\frac{\mu_0}{4 \pi} i^{2}(\frac{d \vec{\ell} \times \vec{r}}{r^{2}})$
(c) $d \vec{B}=\frac{\mu_0}{4 \pi} i^{2}(\frac{d \vec{\ell} \times \vec{r}}{r})$
(d) $d \vec{B}=\frac{\mu_0}{4 \pi} i(\frac{d \vec{\ell} \times \vec{r}}{r^{3}})$
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Answer:
Correct Answer: 49. (d)
Solution:
- (d) According to Biot Savart law,
$d \vec{B}=\frac{\mu_0}{4 \pi} \frac{i(d \vec{\ell} \times \vec{r})}{r^{3}}$
