We have to compute the escape speed for an electron from the surface of a uniformly charged sphere of radius 1.22 cm and total charge . We may neglect gravitational forces.

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Potential energy of an electron at the surface of a uniformly charged sphere of radius and total charge is

Its potential energy at will be zero.

Escape speed is defined as the minimum speed that a particle must have so that it may escape to It implies that the sum of the kinetic energy and the potential energy of the electron on the surface of the charged sphere should be zero. That is

or