Chapter 23, Problem 23.90CP

A particle of mass m and charge q moves at high speed along the x axis. It is initially near x = –∞, and it ends up near x = +∞. A second charge Q is fixed at the point x = 0, y = –d. As the moving charge passes the stationary charge, its x component of velocity does not change appreciably, but it acquires a small velocity in the y direction. Determine the angle through which the moving charge is deflected from the direction of its initial velocity.