A charged particle is fired at an angle `theta` to a uniform magnetic field directed along the x-axis. During its motionalong a helical path, the particle will

Options

A. never move parallel to the `x`-axis
B. move parallel to the `x`-axis once during every rotation for all values of `theta`
C. move parallel to the `x`-axis at least once during every rotation if `theta=45^(@)`
D. never move perpendicular to the `x`-direction

Answer

A, D