## 2008-10-09

### Electric Field

A charged object can exert an attractive force on an oppositely charged object or neutral object even when they are not in contact.

Similarly, the charged object can repel another object of the same charge. The electric force acts over the distance separating the two objects. This can be explained by the concept of electric field.

An electric field is said to exist in the region of space around a charged object. When another charged object enters this electric field, the field exerts a force on it.

In order to visualize the electric field, we draw a series of lines to indicate the direction of the electric field at various points in space. The direction of these electric field lines is the direction of the force that would be exerted on a small positive charge placed at that point.

The principles involved in drawing electric field lines are:

• Electric field lines always extend from a positively-charged object to a negatively-charged object, from a positively-charged object to infinity, or from infinity to a negatively-charged object,
• Electric field lines never cross each other,
• Electric field lines are most dense around objects with the greatest amount of charge,
• At locations where electric field lines meet the surfaces of an object, the lines are perpendicular to the surface.