A charged particle moves with velocity $v$ in a uniform magnetic field $\overrightarrow B $. The magnetic force experienced by the particle is
A
Always zero
BZero, if $\overrightarrow B $ and $\overrightarrow {v\,} $ are parallel
CZero, if $\overrightarrow B $ and $\overrightarrow {v\,} $ are perpendicular
D
Never zero
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BZero, if $\overrightarrow B $ and $\overrightarrow {v\,} $ are parallel
b $\overrightarrow F = q(\overrightarrow v \times \overrightarrow B )$; if $\overrightarrow v ||\,\overrightarrow B $ then $\overrightarrow F = 0$
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