Question

Which of the following is correct?

• A. motion of the particle is non-periodic but $y$ and $z$-position co-ordinates vary in a periodic manner
• B. motion of the particle is non-periodic but $x$ and $y$-position co-ordinates vary in a periodic manner
• C. motion of the particle is non-periodic but $x$ and $z$-position co-ordinates vary in a periodic manner
• D. motion of the particle is periodic and all the position co-ordinates vary in a periodic manner

Answer 1

Answer: (C)

The particle follows a helical path. Due to force acting on particle on in $x$ and $y$ direction, it varies periodically in these directions to form helical surfaces.

However the motion itself is not periodic because it has a $v_x$ component.