An electric field, often referred to as an E field, is a force field that exists in space, particularly when forces act at a distance between charged objects. The field is visualized and represented by field lines connecting units of positive charge (representing the absence of electrons) with units of negative charge. The number of field lines is conventionally used to indicate the quantity of charges involved. These lines are symbolic and connect charged objects, serving as a visual representation of the force field.
The nature of the electric field is determined by placing a small test charge within the field. This test charge must be sufficiently small to avoid altering the field’s nature during measurement. While the test charge may be a hypothetical concept, it plays a crucial role in understanding the forces present in the field. Field lines are drawn with small arrows indicating the direction of the force experienced by the test charge. The density of the lines reveals the strength of the force, with lines being closest together near charged objects where the forces are greatest.
It’s important to note that the electric field exists throughout all space, not just along the lines. The lines are a representation, and at every point in space, the force has both magnitude and direction, making the electric field a vector field.
In the context of Figure 1, if two spheres are relatively close together, and one is moved far away, the electric field on the remaining sphere persists. The lines leaving the near sphere remain evenly spaced around the sphere, indicating uniform spacing of charges on the sphere’s surface. This unique uniform spacing is specific to a sphere, as charges on other conductor shapes arrange themselves to minimize energy storage in the resulting electric field. The concept of field energy storage is introduced, and its implications are mentioned, with further details promised in subsequent sections.