Question

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

• A.
• B. $\vec { B } \| \vec { v }$
• C. It obeys inverse cube law.
• D. It is along the line joining the electron and point of observation.

Answer 1

Answer: (A)

Answer 2

Magnetic field produced by charges moving with velocity $\overrightarrow { \mathrm { V } }$ at a distance r is

$\overrightarrow { \mathrm { B } } = \left( \frac { \mu _ { 0 } } { 4 \pi } \right) \cdot \mathrm { q } \frac { \overrightarrow { \mathrm { v } } \times \hat { \mathrm { r } } } { \mathrm { r } ^ { 2 } }$

Therefore $\vec { B } \perp \vec { v }$