Question

Moving electron (velocity v) produces a magnetic field B such that:

• A. B is perpendicular to v.
• B. B is parallel to v.
• C. Angle between B and v is 45 degrees.
• D. B is opposite in direction to v.

Hint:

Right-Hand Rule: Your thumb is velocity, fingers are the field—they are at 90 degrees!

Answer 1

The Correct Option is A

Step 1: Concept
The magnetic field produced by a moving charge is described by the Biot-Savart Law for a point charge: $\vec{B} \propto \vec{v} \times \vec{r}$.

Step 2: Meaning
The cross product ($\times$) of two vectors results in a third vector that is perpendicular to the plane containing the original two.

Step 3: Analysis
Since $\vec{B}$ is proportional to the cross product of velocity ($\vec{v}$) and the position vector ($\vec{r}$), the magnetic field vector $\vec{B}$ must be perpendicular to the velocity vector $\vec{v}$.

Step 4: Conclusion
Therefore, the magnetic field generated by the moving electron is always perpendicular to its direction of motion. Final Answer: (A)