Question

When a charged particle moving with velocity $\vec{v}$ is subjected to a magnetic field of induction $\vec{B}$, the force on it is non-zero. This implies the :-

• A. Angle between $\vec{V}$ and $\vec{B}$ is either zero or $180^{\circ}$
• B. angle between $\vec{V}$ and $\vec{B}$ is necessarily $90^{\circ}$
• C. angle between $\vec{V}$ and $\vec{B}$ is necessary $90^{\circ}$
• D. angle between $\vec{V}$ and $\vec{B}$ can have at value other than zero and $180^{\circ}$

Answer 1

Answer: (D)

angle between $\vec{V}$ and $\vec{B}$ can have at value other than zero and $180^{\circ}$

Answer 2

$\vec{ F }= q (\vec{ v } \times \vec{ B })=avB\, \sin \theta\, \hat{ n }$
Therefore when $\theta=0^{\circ}$ or $\theta=180^{\circ}, F =0$