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 velues 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)

Explanation

When the particle moves in a helical path, the plane of the helical path will be slightly inclined with x-axis. Hence, options (a) and (d) are correct.
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