A small charged ball of mass m and charge q is hanging at the end of a non-stretchable thread of length l in a magnetic field of induction B. The ball is brought to a height H=87l while holding the thread straight and then it is let free. The gravitational acceleration is g and the direction of the magnetic field is perpendicular to the plane of the pendulum. It is also known that q2B2l=43m2g applies. What is the trajectory of the ball?
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