The next 5 questions all have to do with the diagram shown, on which I have placed an electron at the origin. The grid spacing is 1 Angstrom per small square. Now place an atomic nucleus with 15 protons on positive x-axis, at x = 5.4 Angstroms. How much work did it take you to bring this nucleus in from 1 m away?     40.0 eV     32.0 eV     60.0 eV     36.0 eV

A charge of 36.3 nC is transferred to a neutral copper ball of radius 4.35 cm. The ball is not grounded. The excess electrons spread uniformly on the surface of the ball. What is the number density (number of electrons per unit surface area) of excess electrons on the surface of the ball?

You are working on a research project in which you must control the direction of travel of electrons using deflection plates. You have devised the apparatus shown in Figure P22.28. The plates are of length = 0.500 m and are separated by a distance d = 3.00 cm. Electrons are fired at vi = 5.00 106 m/s into a uniform electric field from the left edge of the lower, positive plate, aimed directly at the right edge of the upper, negative plate. Therefore, if there is no electric field between the plates, the electrons will follow the broken line in the figure. With an electric field existing between the plates, the electrons will follow a curved path, bending downward. You need to determine (a) the range of angles over which the electron can leave the apparatus and (b) the electric field required to give the maximum possible deviation angle. Figure P22.28

Suppose Earth and the Moon each carried a net negative charge Q . Approximate both bodies as point masses and point charges. (a) What value of Q is required to balance the gravitational attraction between Earth and the Moon? (b) Does the distance between Earth and the Moon affect your answer? Explain. (c) How many electrons would be needed to produce this charge?