Question

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

• A. $B\botv$
• B. $B\parallelv$
• 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
$\overset{ \rightarrow }{B}=\frac{\left(\mu \right)_{0}}{4 \pi }\frac{q \left(\overset{ \rightarrow }{v} \times \overset{ \rightarrow }{r}\right)}{r^{3}}$
Where, $\overset{ \rightarrow }{B}=$ Magnetic field Produced
$\overset{ \rightarrow }{v}=$ Velocity of charged particle
$\overset{ \rightarrow }{r}=$ Position vector of point with respect to charge
$\mu _{0}=$ Magnetic permeability of free space
$\because $ It is a cross product $\overset{ \rightarrow }{v}$ and $\overset{ \rightarrow }{r}$
$\therefore $ $\overset{ \rightarrow }{B}$ Is perpendicular to $\overset{ \rightarrow }{v}$ .