An electrostatic precipitator is a device used in industry to remove pollution from exhaust gas. It consists of a long thin wire surrounded by a conducting cylinder, such that a potential about 5 x 104 volts is maintained between the negative wire and the positive cylinder. (See figure.)
The resulting electric field inside the cylinder varies inversely with the distance from the center wire. Neutral particles of pollution are attracted to the center wire. The electric field near the wire is strong enough (greater than about 3 x 106 N/C) to ionize air, so the pollution particles are ionized negatively. They are attracted to the outer cylinder, where they collect and are eventually removed.
A typical energy requirement for such a device is about 300 Joules for each cubic meter of gas processed.
Note: The charge on an electron is –1.6 x 10–19 C. Point A is in the plane of the page.
If a sodium ion is at point A, in what direction would it experience a force?