Consider an electron on the surface of a uniformly charged sphere of radius 1.2 cm and total charge 1.4 10-15 C. What is the "escape speed" for this electron

electric potential of electron

= k Qq / r

= - 9 x 10⁹ x 1.4 x 10⁻¹⁵ x 1.6 x 10⁻¹⁹ / (1.2 x 10⁻²)

= - 16.8 x 10⁻²³ J

If v be the escape velocity

1/2 m v² = potential energy of electron

= 1/2 x 9.1 x 10⁻³¹ x v² = 16.8 x 10⁻²³

v² = 3.69 x 10⁸

v = 1.92 x 10⁴ m / s