A proton (or charged particle) moving with velocity $v$ is acted upon by electric field $E$ and magnetic field $B$. The proton will move undeflected if

  • A

    $E$ is perpendicular to $B$

  • B

    $E$ is parallel to $v$ and perpendicular to $B$

  • C

    $E$, $B$ and $v$ are mutually perpendicular and $v = \frac{E}{B}$

  • D

    $E$ and $B$ both are parallel to $v$

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