Question

Biot-Savart law indicates that the moving electrons (velocity $v$ ) produce a magnetic field $B$ such that:

• A. $B\perp v$
• B. $B\parallel v$
• C. it obeys inverse cube law.
• D. it is along the line joining the electron and point of observation.

Answer 1

Answer: (A)

According to Biot-Savart law
$\vec{B}=\frac{{\mu }_0}{4\pi }\frac{q\vec{v}\times \vec{r}}{r^3}$
Where, $\vec{B}=$ Magnetic field Produced
$\vec{v}=$ Velocity of charged particle
$\vec{r}=$ Position vector of point with respect to charge
${\mu }_0=$ Magnetic permeability of free space
$\because$ It is a cross product $\vec{v}$ and $\vec{r}$
$\therefore \vec{B}$ Is perpendicular to $\vec{v}$