Final answer:
Placing charge on the particles helps them stick to an object's surface through electrostatic attraction.
Step-by-step explanation:
When electrically charged paint or powder particles are sprayed on a neutral metal object, placing charge on the particles helps them to stick to the object's surface through the process of electrostatic attraction. The electrically charged particles are attracted to the surface of the object, which has an opposite charge. This attraction overcomes the mutual repulsion between like charges and allows the particles to adhere to the surface.
For example, when the object is a conductor, the electric field created by the charge on the particles is perpendicular to the surface. This perpendicular electric field tends to bring the charged particles in perpendicularly, resulting in a more even and controlled coating. Corners and points on conductors receive extra paint due to the concentration of electric field lines.
In industrial settings, electrostatic painting is used to achieve an even coat on odd-shaped surfaces and reach difficult-to-access areas.