A narrow beam of identical ions with specific charge q/m, possessing different velocities, enters the region of space, where there are uniform parallel electric and magnetic fields with strengths `E and B`, at the point O. The beam direction coincides with the x-axis at the point O. A plane screen oriented at right angles to the x-axis is located at a distance `I` from O. Find the equation of trace that the ion leaves on the screen. Demonostrate that at `z lt lt l`, it is the equation of a parabola.

Answer

`[z^(2)-((B^(2)l^(2)q)/(2mE))y]`