A negatively charged particle having magnitude of charge
Q = 0.1 c and mass m = 200 gm moves with speed v = 10m/s
Enters a region having magnetic field B = 4Tmaking an angle
60° with X axis as shown in figure. The direction of magnetic
Field is out of the X–Y plane. A convex lens is placed at a
Distance 14.3 m from origin. Region of magnetic field starts
From origin and extends till lens. Focal length of lens is 50cm.
Take x axis as principle axis.For more details see the image.
What is the frequency of revolution.

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